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Book 



EDWARD NELSON DINGLEY 
COLLECTION 

PRESENTED BY HIS WIFE 



1 



THE 

PLURALITY OF WORLDS. 



" Lo, these are parts of His ways : but how little a portion 
la heard of Him ? the thunder of His power who can under- 
stand ? " — Job xxvi. 14. 



OTHER WORLDS 
THAN OURS 



THE PLURALITY OF WORLDS 

STUDIED UNDER THE LIGHT OF RECENT 

SCIENTIFIC RESEARCHES 



RICHARD A. PROCTOR, B.A., F.R.A.S. 

AUTHOR OF SATURN AND ITS SYSTEM, SUN-VIEWS OF THE EARTH, 
HALF-HOURS WITH THE TELESCOPE, ETC. 



Not to this evanescent speck of earth 
Poorly confined — the radiant tracts on high 
Are our exalted range ; intent to gaze 
Creation through, and from that full complex 
Of never-ending wonders, to conceive 
Of the Sole Being right. Thomson. 



NEW YORK 
D. APPLE TON AND COMPANY 
I 



QBsri 



Authorized Edition. 



Gift from 
Mrs. Edwarb N. Djngley 
July 11 1932 



PREFACE. 



The general purpose I have had in view in writ- 
ing the present treatise will be gathered from the 
introductory pages; but I wish to offer here a few 
remarks on certain points of detail. 

It will be seen that, on many of the subjects dealt 
with in this work, I have propounded views which 
differ from those usually accepted. I have not done 
this from any love of novelty, nor from any desire to 
attract attention by hizarre or fanciful theories. Each 
of the new views here presented has been the result 
of a careful study of the subject dealt with, and I have 
searched as anxiously for considerations opposed to 
any novel theory as for arguments in its favor. If 
others should be more successful than I have been in 
finding reasons for rejecting any of my views, I shall 
be ready to abandon them without regret. I trust I 
am free from that weakness which forces a man to re- 
gard every theory he has once advocated as a matter 



5 PREFACE 

to be defended at all hazards. ]S r o weakness more 
mischievously affects the work of the student of 
science. As Faraday said, " Truth should be the pri- 
mary object of the philosopher ; " and this can never 
be the case if, where he imagines he holds a theory, 
the theory has in truth possession of him. 

Some among my readers will recognize, in the 
views here presented, the growth of ideas which 1 
have dealt with consecutively, with more or less ful- 
ness, in the pages of several quarterly, monthly, and 
weekly serials, and in one of our leading daily news- 
papers. I refer to this, because it has happened to 
me several times lately to be accused of plagiarism, 
when I have had occasion, in developing fresh ideas 
on a subject, to repeat statements which (unknown of 
course to my accusers) had proceeded from mj own 
pen. It is not often one is accused of stealing one's 
own ideas, but that is a pleasure I have more than 
once been enabled to enjoy of late, and I here present 
my compliments to those who (anonymously or other- 
wise) have afforded me that luxury. 

Wherever it has been in accordance with the cus- 
tom of any journal, however, I have always written 
under my own name. 

Since the manuscript of this work was placed id 
the printers' hands, I have obtained fresh evidence on 



PREFACE. 7 

some ol the theories dealt with in the following 
pages. 

One of the most surprising phenomena ever wit- 
nessed by the telescopist — a phenomenon I had read 
of lono; since, but had not thought of in connection 
with my subject — seems to me to afford stronger evi- 
dence than any adduced in the text, in favor of my 
theory that the major planets are subsidiary suns sup- 
plying heat (if not a minute proportion of light even) 
to their satellites. I refer to the observation made by 
Admiral Smyth, that on one occasion the second sat- 
ellite of Jupiter, twelve minutes after entering on the 
disk of the planet, was seen outside the limb, "where 
it remained four minutes, and then suddenly van- 
ished." Two other equally competent observers, 
Maclear and Pearson, witnessed the same phenome- 
non. " Here," says "Webb, " explanation is set at defi- 
ance." But it is precisely where explanation seems 
set at defiance, that the true student of ^Nature is most 
hopeful of gaining instruction. The observation is 
very startling, it is true ; and the explanation may be 
expected to be also surprising. But I think it is not 
far to seek. The satellite cannot have retraced its 
course ; Jupiter cannot have shifted his place ; our 
atmosphere cannot be in question: surely, when all 
these explanations are eliminated, our task is rendered 



8 PREFACE. 

easier instead of more difficult. A change of shape in 
Jupiter, corresponding to that which I have endeav- 
ored to exhibit as explaining Saturn's occasional as- 
sumption of the square-shouldered aspect, would obvi- 
ously account for the phenomenon. We know that 
Schroter suspected an apparent flattening of portions 
of Jupiter's outline. Here we have an effective con- 
firmation of that long-doubted observation. If we 
consider the matter rightly, the observation made 
simultaneously by Smyth, Maclear, and Pearson, 
makes that view all but certain, which in the text I 
have presented only as a highly-probable hypothesis. 

In preparing the Maps for my new Atlas (now 
nearly ready), I have detected signs of systematic ag- 
gregation among stars visible to the naked eye, which 
seem to me to place beyond all question the fact that 
Sir "William Herschel adopted an erroneous hypothesis 
as the basis of his system of star-gauging. The fact 
that about one-third of the lucid stars are collected in 
a region having the greater Magellanic Cloud nearly 
in its centre, and covering less than one-sixth of the 
heavens, has never yet, so far as I am aware, been 
noticed. Supplemented by other facts detected during 
the work of transferring the stars of the British As- 
sociation Catalogue to my Maps, the existence of this 
rich region around the ^Tubeculse disposes at once of 



PREFACE. 9 

the hypothesis of a generally uniform distribution 
within the sidereal system. I shall be enabled, by 
Mr. Brothers's kindness, to illustrate my Lecture on 
the Stars at the. Royal Institution on May 6th by 
means of photographs of the Maps which thus con- 
clusively (at least in my opinion) establish the theory 
that there exist special and discernible laws of aggre- 
gation among the lucid stars. 

I may add in this place that it is not the case, as 
has been recently asserted, that my theories respect- 
ing the sidereal system have been founded on the 
discovery that certain nebulae are gaseous. That dis- 
covery, so far from being opposed to the theories of 
Sir William Herschel, afforded most striking evidence 
of his wonderful reasoning powers, since he had been 
led to express his firm conviction that many nebulae 
are gaseous, had confidently asserted that the Orion 
nebula is so, and had even anticipated the discovery 
of the variability of the irregular nebulae, recently 
effected by Le Sueur of Melbourne. 

My theory respecting the sidereal system has been 
based on the signs of systematic aggregation among 
the lucid stars, and of a more intimate association of 
those stars with the Milky Way than could be ex- 
pected were Sir William Herschel's fundamental 
theory correct. My first paper on the subject, in the 



io PREFACE. 

Intellectual Observer for August, 1867, was entitled 
" Notes on Star-Streams ; " and it was only while 
inquiring into the nature of stellar aggregation that 
I was led to notice the laws of nebular distribution, 
and so to inquire into the relations between stars and 
nebulse. I take this opportunity of thanking my kind 
friend, the editor of the Intellectual Observer and 
Student, for the exceptional liberality with which 
he has found a place for views professedly opposed 
to generally-received opinions. 

The theory brought forward in the chapter on 
Meteors and Comets is not altogether new. The 
general idea on which it is grounded has been dealt 
with by Mayer and Thompson, while the relation be- 
tween the motions of discrete bodies and the forma- 
tion of systems of orbs has been dealt with by Sir 
John Herschel, in considering his father's hypotheses 
respecting the nebulse. That idea, however, presented 
itself independently to my mind when I was writing 
my treatise on Saturn (at which time . my acquaint- 
ance with scientific literature was very limited in- 
deed), and is definitely stated in Note B of the Ap- 
pendix to that work. The line of reasoning is wholly 
new, I believe, by which I have endeavored to show 
that those peculiarities of the solar system which 
have hitherto been regarded as affording the strongest 



PREFACE. 11 

objection to the hypothesis of development, may be 
regarded as in reality the direct result of the processes 
by which the solar system has reached its present con- 
dition. In the preface to my treatise on Saturn I 
touched on the possibility that some such explanation 
of those peculiarities might be found, remarking that 
in the rings of Saturn astronomers may one day rec- 
ognize the action of the processes by which the solar 
system has attained its present state. 

In the chapter on the Sun I have entered at some 
length into the subject of the solar corona, partly be- 
cause that subject is full of interest in view of the 
approaching total solar eclipse visible in the south of 
Europe, and partly because I have seen with regret 
that an erroneous theory of the corona has been re- 
cently promulgated, which seems likely at the present 
conjuncture to affect mischievously the progress of re- 
search into this interesting question of solar physics. 
I have heard with much pleasure that the Astronomer 
Royal, at the last meeting of the Astronomical Socie- 
ty, altogether repudiated any share in starting this 
theory. Although I had seen his name associated 
with it, I had always thought it incredible that a 
mathematician so skilful and clearsighted should have 
advanced or adopted so ill-considered an hypothesis. 

I tender my best thanks to Mr. Browning, F. E. 



l2 PREFACE. 

A. S., for the beautiful colored pictures of Jupiter and 
Saturn, which illustrate the chapters on those planets ; 
and to Mr. Brothers, F. E. A. S., for his careful revi- 
sion of the proof-sheets, and the detection of more than 
one error which had escaped my scrutiny. 

Richard A. Prootor. 

Lokdon, April 12, 1870. 



CONTENTS. 



CH4V. PAGE 

INTRODUCTION . . . . . .17 

I. — "What the Earth teaches us 22 

II. — What we learn from the Sen . . . .35 

III. — The Inferior Planets .... 71 

IV. — Mars, the Miniature of our Earth . , .97 

V. — Jupiter, the Giant of the Solar System . . 123 

VI. — Saturn, the Ringed World . 159 

VII. — Uranus and Neptune, the Arctic Planets . . 176 

Till. — The Moon and other Satellites 187 

IX. — Meteors and Comets ; their Office in the Solar System 202 

X. — Other Suns than ours . . . 230 

XL — Of Minor Stars, and of the Distribution of Stars is 

Space . . , 258 

XII. — The Nebulae, are they External Galaxies ? 282 

XIII. — Supervision and Control , 805 



ILLUSTKATIOtfS. 



TEE PLANET JUPITER ^colored) .... Frontuplcoe. 

FOUR TELESCOPIC DRAWINGS OF MARS {colored) to face p. 104 

CHART OF MARS, ON THE STEREOGRAPHIC PROJEC- 
TION {colored) to face p. 105 

THE PLANET JUPITER (BROWNING) . . . page 146 

TEE PLANET SATURN {colored) .... to face p. 167 

THE GALACTIC CLOVEN FLAT RING {plan) . . . page 262 

THE GALACTIC CLOVEN FLAT RING {section) . . page 262 

THE GALACTIC FLAT RING, MODIFIED IN ACCORDANCE 
WITH THE OBSERVED PECULIARITIES OF TILE 
MILKY WAY page 264 

THE MILKY WAY REGARDED AS A SPIRAL . . . page 268 

THE PROPER MOTIONS OF STARS IN GEMLNI AND CAN- 
CER ......... page 278 

OBSERVED PROPER MOTIONS OF STARS LN URSA MAJOR 

AND NEIGHBOREOOD page 279 

OBSERVED PROPER MOTIONS OF STARS IN HEAD OF 

ARIES page 280 

THE NEBULA, MESSEER 17 . . . to face p. 302 



OTHER WORLDS THAN OURS. 



INTRODUCTION. 

Astronomy and Geology owe much, of their charm 
to the fact that they suggest thoughts of other forms of 
life than those with which we are familiar. Geology 
teaches us of days when this earth was peopled with 
strange creatures such as now are not found upon its 
surface. We turn our thoughts to the epochs when 
those monsters throve and multiplied, and picture to 
ourselves the appearance which our earth then pre- 
sented. Strange forms of vegetation clothe the scene 
which the mind's eye dwells upon. The air is heavily 
laden with moisture to nourish the abundant flora; 
hideous reptiles crawl over their slimy domain, battling 
with each other or with the denizens of the forest ; 
huge bat-like creatures sweep through the dusky 
twilight which constituted the primeval day; weird 
monsters pursue their prey amid the ocean-depths : 
and we forget, as we dwell upon the strange forms 
which existed in those long-past ages, that the scene 
now presented by the earth is no less wonderful, and 



18 OTHER WORLDS THAN OURS. 

that the records of our time may perhaps seem one day 
as perplexing as we now find those of the geological 
eras. 

Astronomy has a kindred charm. We cannot in- 
deed examine the actual substance of living creatures 
existing upon other celestial bodies ; we cannot even 
picture to ourselves their appearance or qualities ; and 
only in a few instances can we even form any con- 
ception of the conditions under which they live. But 
we see proofs on all sides that, besides the world on 
which we live, other worlds exist as well cared for and 
as nobly planned. Nay, we see globes by the side of 
which our earth would seem but as a tiny speck ; we 
trace these globes as they sweep with stately motion 
on their appointed courses ; we watch the return of 
day on the broad expanse of their surface ; and we see 
systems of satellites which are suspended as lights for 
their nocturnal skies. We further find that our sun is 
matched by a thousand thousand suns amid the im- 
measurable depths of space ; and the mind's eye pic- 
tures other worlds like those which course around the 
sun, travelling in stately orbits around his fellow- 
luminaries. 

Long, however, before the wonders of modern astron- 
omy had been revealed to us, men of inquiring minds 
seem to have been led, as by an irresistible instinct, to 
examine into the resemblance which may exist between 
our world and other worlds surrounding it on every 
hand. It has not been the mere fanciful theorizer 
who has discussed such questions, but men of the 
highest eminence in science. In long-past ages Anaxi- 



INTR OD UCTION. 1 g 

mander and Pythagoras studied the subject of other 
worlds than ours ; later, such men as Huyghens, 
G-alileo, and Newton, have dwelt upon the same in- 
teresting theme ; while, in our own day, Whewell and 
Brew r ster have employed their scientific and dialectic 
Ekil] in defending rival theories upon the subject. 

Undoubtedly a large share of the interest with 
which the question of other worlds than ours has been 
regarded, is due to the fact that, as the science of as- 
tronomy has progressed, the subject has continually 
presented itself under new aspects. The question, in 
fact, is one of those which are ever new and ever old. 
It has all the charm belonging to subjects which men 
in all ages have delighted to discuss, while it is asso- 
ciated in the most intimate manner with the progress 
of modern science. With what a charm of novelty, 
for instance, the discussion between "Wliewell and 
Brewster invested the subject ! No doubt a large 
portion of that charm was due to the personal qualities 
of the two disputants. Yet, despite the skill with 
which each of them presented the arguments belong- 
ing to his own side of the controversy, few could have 
read with any interest a discussion on a subject so 
well worn, had it not been that the arguments were 
drawn from the discoveries which had recently been 
made by astronomers. Nor was it uninteresting to 
notice how these discoveries at once seemed to acquire 
a new interest when they were associated with the 
subject of life in other worlds. Facts which had 
attracted little notice at the time of their discovery, at 
once assumed importance, when it was seen how they 



2 o OTHER WORLDS THAN OURS. 

bore on the rival views which Whewell and Brewster 
were enforcing. The interest with which the public re- 
gard many of these discoveries may, indeed, be said to 
date from the controversy between those eminent men. 

No very long interval, if we connt by years, has 
elapsed since the " Plurality of Worlds " and " More 
Worlds than One " were written. Yet so rapidly has 
science progressed, that already the subject of life in 
other worlds has assumed a new aspect. Arguments 
which were hypothetical thirty years ago have either 
become certainties or been disproved. Doubtful points 
have been cleared up ; a new meaning has been found 
even in those facts which were well known to both the 
disputants; and lastly, a new mode of research has 
been devised, which has not only revealed a number 
of surprising facts, but promises to work yet greater 
marvels in the years which are to come. 

One is thus invited to discuss anew a subject which 
but a few years since seemed thoroughly sifted by 
the inquiries of the two eminent philosophers I have 
named. We stand in a position much more favorable 
for the formation of just views than that from which 
Whewell and Brewster surveyed the planetary and 
stellar systems. Never, since men first explored the 
celestial depths, has a series of more startling dis- 
coveries rewarded the labors of astronomers and 
physicists than during the past few years. Unhoped- 
for revelations have been made on every side. Anal 
ogies the most interesting have brought the distant 
orbs of heaven into close relationship with our own 
earth, or with the central luminary of the planetary 



INTRODUCTION- 21 

scheme. And a lesson lias been taught us which bears 
even more significantly on our views respecting the 
existence of other worlds : we have learned to recog- 
nize within the solar system, and within the wondrous 
galaxy of which our sun is a constituent orb, a variety 
of structure and a complexity of detail, of which but a 
few years ago astronomers had formed but the most 
inadequate conceptions. 

My object, then, in the pages which follow, is not 
solely to establish the thesis that there are other worlds 
than ours, but to present, in a new and I hope interesting 
light, the marvellous discoveries which have rewarded 
recent scientific researches. Judged merely according 
to their direct significance, these discoveries are well 
calculated to excite our admiration for the wonderful 
works of God in His universe, and for the far-reaching 
scope of the mental powers which He has given to His 
creature Man. But it is when we consider recent 
discoveries in their relation to the existence of other 
worlds, when we attempt to form a conception of the 
immense varieties of the forms of life corresponding 
to the innumerable varieties of cosmical structure dis- 
closed by modern researches, that we recognize the 
full significance of those discoveries. Although the 
growth of our knowledge is ever accompanied by a 
proportional growth of our estimate of the unknown 
we seem already entitled to say that we have 

Come on that which is, and caught 
The deep pulsations of the world, 
iEonian music, measuring out 
The steps of time. 



CHAPTEE I. 

WHAT OUR EARTH TEACHES US. 

.Befoke proceeding to consider the various circum- 
stances under which the worlds or systems which 
surround us appear to subsist, it may be well to 
inquire how far we have reason to conclude, from the 
consideration of our own earth and its inhabitants, 
that the Creator has designed the orbs which exist 
throughout space for the support of living creatures. 

It would not be just to argue directly from the fact 
that the earth is inhabited to the conclusion that the 
other planets are inhabited also, nor thence to the con- 
clusion that other stars have, like our sun, their attend- 
ant worlds, peopled with various forms of life. An 
analogy founded on a single instance has no logical 
force. And it is doubtful whether we have not, in the 
moon, an instance which would as effectually serve to 
support a directly opposite conclusion. It seems all 
but certain, as we shall presently have occasion to 
show, that no part of the moon's globe is inhabited by 
living creatures. Certainly she is inhabited by none 
which bear the least resemblance to those existing on 
our earth. Thus it might fairly be urged that, since 



WHAT OUR EARTH TEACHES US. 23 

one of the two orbs respecting which we know most 
appears to be uninhabited, there remains no probable 
argument in favor of the view that other orbs besides 
our earth are the abode of living creatures. 

Yet the earth in reality supplies an argument of 
great force, when we consider the evidence she presents 
in another light. The mere fact that this world is in- 
habited is, as we have seen, little ; but we shall find 
that the way in which life is distributed over the 
earth's surface is full of significance. 

If we range over the earth, from the arctic regions 
to the torrid zone, we find that none of the peculiarities 
which mark the several regions of our globe suffice to 
banish life from its surface. In the bitter cold within 
the arctic circles, with their strange alternations of long 
summer days and long winter nights, their frozen seas, 
perennial ice, and scanty vegetation, life flourishes in a 
hundred various forms. On the other hand, the torrid 
zone, with its blazing heat, its long-continued droughts, 
its strange absence of true seasonal changes, and its 
trying alternations of oppressive calms and fiercely- 
raging hurricanes, nourishes even more numerous 
and more various forms of life than either of the great 
temperate zones. Around mountain-summits as in the 
depths of the most secluded valleys, in mid-ocean as in 
the arid desert, in the air as beneath the surface of the 
earth, we find a myriad forms of life. 

But this is far from being all. Various as are the 
physical habitudes which we encounter as we travel 
o^er the surface of our globe, we are able to trace the 
existence of other varieties even more remarkable. 



24 OTHER WORLDS THAN OURS. 

The geologist has been able to turn back a few leaves 
of the earth's past history, and, though the pages have 
been defaced and mutilated by Time's unsparing hand, 
he is yet able to read in them of many strange vicissi- 
tudes to which the continents and oceans of our globe 
have been exposed. But, far back as he can trace the 
earth's history, and already he counts her age by mill- 
ions of years,* he finds no evidence of an epoch when 
life was absent from her surface. Nay, if he reads 
aright the mysterious lesson which the blurred letters 
teach him, he is led to believe that, at the most distant 
epoch to which his researches have extended, there 
was the same wonderful variety in the forms of life 
as at the present day. He can, indeed, find the scat- 
tered remains of only a few of those old-world 
creatures ; but he recognizes, in those which have been 
preserved, the clearest evidence that thousands of 
others must have existed around them. He knows 
that, of a million creatures now existing, scarcely one 
will leave to future ages any record of its existence ; 
he sees whole races vanishing from the earth, leaving 
no trace behind them ; and he is thus able to form an 

* The results of the recent deep-sea dredging expeditions, though 
they have an obvious bearing on the question of the relative ages of the 
various strata of our earth, do not appreciably affect our estimate of the 
range of time during which this world has been the abode of living 
creatures. We can no longer assume that adjacent rocks which differ in 
character are necessarily different in age : but we have enough evidence, 
from superimposed strata, to prove the enormous antiquity of the earlier 
formations. The researches of Dr. Carpenter and his fellow-workers 
have a most important bearing, however, on the subject of the present 
chapter, and supply a more forceful analogy, perhaps, than any dwelt on 
in the text, in favor of the view that, under the widest varieties of con. 
lition, Nature may be most prodigal of life. 



WHAT OUR EARTH TEACHES US 2S 

estimate of the enormous extent by which the creatures 
and races of which he can learn nothing must have out- 
numbered those whose scattered remains attest their 
former existence upon the earth. 

Here, then, we have analogies which there is no 
mistaking. We see that not only is Nature careful to 
fill all available space with living forms, but that no 
time over which our researches extend has found her 
less prodigal of life. We see that, within very wide 
limits, she has a singular power of adapting living 
creatures to the circumstances which surround them. 
Nor is this lesson affected — like the general lesson 
drawn from the mere fact of the earth's being inhabited 
—by any thing we can learn from the aspect of our 
satellite. For the arguments against the presence of 
living creatures on the moon are founded on the evi- 
dence we have that the physical habitudes of that orb 
are outside the limits — wide as they seem to be — ■ 
within which Nature can effect the adaptation we have 
spoken of. 

In fact, if we consider rightly, the argument which 
has been drawn from the moon's presumed unfitness to 
be the abode of living creatures is so founded on ter- 
restrial analogies as to leave the contrary argument 
unaffected. We have to assume that the argument 
drawn from the analogy of the earth is forceful before 
we can form any opinion at all respecting the moon's 
habitability. And, in any case, no argument can be 
drawn from the moon's unfitness for the support of 
life, against the view that, where orbs fit for the sup- 
port of life exist, there Nature has provided such 



26 OTHER WORLDS THAN OURS. 

classes of living creatures as are adapted to the special 
habitudes of those orbs. 

The moon teaches us, however, that the Creator 
has not intended all the celestial bodies to be at all 
times habitable. The sun also teaches the same lesson. 
And it is necessary that we should consider how far 
the evidence presented by our own earth may serve to 
elucidate this teaching. We shall see, as we proceed, 
that terrestrial analogies afford a very sure guide in 
the midst of many perplexities which the study of the 
worlds around us presents to our contemplation. 

Let us trace out the various degrees of fitness or 
unfitness for the support of particular forms of life, 
which we recognize in various regions of our earth. 

Often, where there exists so slight a difference be- 
tween two regions of the earth that, to ordinary obser- 
vation, it would appear that the forms of life existing in 
one should be well adapted to the other also, we yet 
find that this is not the case. Some minute peculiarity 
of soil, or climate, or vegetation, will render one region 
absolutely uninhabitable by a race which lives and 
thrives in the other. Darwin mentions several in- 
stances in which an apparently insignificant change in 
the circumstances under which a particular race has 
thriven, and sometimes a change which does not, at 
first sight, appear to be in the least connected with the 
well-being of the race, has led to its gradual disappear 
ance. And it seems demonstrated that even the slow 
processes of change to which every part of the earth 
is subjected would suffice to destroy a number of the 
races now subsisting on its surface, were the character 



WHAT OUR EARTH TEACHES US. 2 j 

istics of those races unalterable. But, as the physical 
habitudes of their abode slowly change, the various 
races of living creatures slowly change also, so as to 
adapt themselves continually to the varying circum- 
stances under which they live. 

The lesson taught us by this peculiarity is very 
obvious. On the one hand, we see that it would be by 
no means sufficient to indicate a general resemblance 
between the physical habitudes of our earth and those 
of some far-distant planet, in order to prove that that 
planet is the abode of living creatures resembling those 
on our own earth. But, on the other hand, we are 
taught that the existence of differences sufficient to 
render a distant planet an unsuitable abode for such 
creatures as we are familiar with, cannot force upon us 
the conclusion that the planet is uninhabited. On the 
contrary, the circumstance we have been considering 
teaches us, that such differences as would suffice to 
banish life of certain kinds are insufficient to banish 
life of all kinds, or even to render less abundant the 
forms of life which exist under those changed condi- 
tions. 

Aud now we may proceed a step farther. On our 
earth we find differences of climate and of physical 
habitudes generally, which are much more important 
than those hitherto dealt with. "We see that not only 
would certain races perish in the long-run, if removed 
from their own abode to other parts of the earth, but 
that, in some instances, the process of destruction would 
be very rapid indeed. If we were to remove the polar 
bears from their arctic fastnesses to tropical, or even 



28 OTHER WORLDS THAN OURS. 

to the warmer parts of temperate regions, a very few 
years would see the end of the whole race. The races 
inhabiting steppes and prairies would quickly perish, 
if removed to mountain-regions. Those accustomed 
to a moisture-laden air and abundant vegetation would 
not survive long if removed to the desert. 

In some races, indeed, we find a power of enduring 
such changes which very far exceeds that possessed by 
other races. Those creatures, for example, which man 
has domesticated seem capable of enduring a variety 
of climate or of circumstances, which would destroy 
the seemingly more vigorous races which have not been 
subdued to the yoke of man.* 

Even man himself, however, though he possesses in 
an unrivalled degree the power of enduring in safety 
the most complete change of climate, scene, and cir- 
cumstances, is yet limited, in a certain sense, in his 
power of migration. The Englishman, for example, 
can endure the fiercest heat of the tropics or the bit- 
terest cold of arctic and antarctic regions. But he 
cannot safely attempt to found true colonies in every 
part of the earth's surface. Our countrymen in India 
must send their children to be reared in England, if 
they wish them to grow up strong and vigorous. 
There can be little doubt that if a thousand men and 

* Humboldt tolls us that " the pliability of the organization of those 
animals which man has subjected to his sway, enables horses, cows, and 
other species of European origin, to lead for a time an amphibious life, 
surrounded by crocodiles, water-serpents, and manatees. When the 
rivers return again to their beds, the horses roam in the savannah, 
which is then spread over with a fine odoriferous grass ; and enjoy, as in 
their native climate, the renewed vegetation of spring." 



WHAT OUR EARTH TEACHES US. 2 g 

women from this country were to settle in certain parts 
of India (not at any time intermarrying with the na- 
tives), the colony wonld have disappeared within a 
couple of centuries. 

Here we have a second degree of unfitness, accord- 
ing to which certain countries would quickly become 
depopulated, if supplied with inhabitants from certain 
other countries. We are taught the same lesson as 
before, but in a more striking manner. We see that 
differences exist within the confines of our own earth, 
which render particular countries absolutely uninhab- 
itable by particular races, insomuch that, though the 
individual might survive, the race itself would quickly 
perish. And we see, on the other hand, that these 
countries are not uninhabited, or even less fully peo- 
pled with living creatures, than seemingly more fortu- 
nate abodes. 

Now, if some impassable barrier prevented the in- 
habitants of one country from visiting others, while 
yet it was possible to learn something of the conditions 
prevailing in other regions, how readily the conclusion 
might be reached, that some at least of those inac- 
cessible regions must be wholly uninhabited, simply 
because their physical habitudes appeared un suited 
to the wants of the only creatures with which the 
observer was familiar. Who would believe, for ex- 
ample, that men can live, and not only live but thrive 
and multiply, in the frost-bound regions within the 
Arctic circle, if travellers had not visited the Esquimaux 
races, and witnessed the conditions under which they 
subsist ? Again, if we knew nothing of India, and 



5 o OTHER WORLDS THAN OURS. 

some one pictured to us the intense heat of the Indian 
sun, the strange alternations of weather which replace 
to the Indian the seasonal changes we are familiar 
with, and all the other circumstances which render 
tropica, regions so different from our English home, 
who could believe that, amid those seemingly un- 
endurable vicissitudes, there are races of men that 
thrive and multiply, even as our people in their tem- 
perate zone ? * 

Therefore, in examining the circumstances of other 
worlds than ours, it will not be sufficient to prove that 
certain orbs would obviously not be habitable by the 
races subsisting on the earth, in order to enforce the 
conclusion that no living creatures subsist at all upon 
their surface. 

Yet another step farther, however. There are 
regions of the earth where the individuals of races 
belonging to other regions quickly perish. The air of 
our own England is death to many creatures. And, 
indeed, there is not a spot in the whole world which 
would not be fatal in a brief space to many animals and 
plants belonging to other regions. Yet each spot, 
though thus fatal to certain races, is inhabited by 
numbers of others, which live and thrive upon its sur- 
face. 

* Perhaps the most striking instance of man's power of living under 
circumstances seemingly the most unfavorable, is to be found in the 
fact that, though the strongest traveller is affected seriously by the rar- 
ity of the air at great elevations, yet races of men live and thrive hi 
Potosi, Bogota, and Quito, and — to use the words of a modern writer — 
that bull-fights should be possible at an elevation at which Saussuro 
hardly had energy to consult his instruments, and where even his guides 
fainted as they tried to dig a small hole in the snow, 



WHAT OUR EARTH TEACEES US. 3, 

Here, then, is our third lesson. We are taught, by 
the analogy of our earth, that it is not even sufficient 
to show that a planet would be an abode quickly fatal 
to all the living creatures subsisting on our globe, to 
prove that it is therefore uninhabited. 

But we have yet a stronger argument to touch on. 
There are regions of our earth to which creatures from 
other regions cannot be removed without being imme- 
diately killed. The warm-blooded animal perishes, if 
placed for a brief space under water. The fish perishes, 
if placed for a brief space on the earth.* What could 
be more wonderful to us, were we not familiar with 
the fact, than that there are living creatures within the 
depths of that ocean, beneath whose surface we our- 
selves, and the land creatures we are familiar with, 
cannot remain alive many minutes ? If fishes could 
reason, how could they believe that creatures can live 
in comfort in that element which is death to them ? 
Yet land and river and sea are alike peopled with 
living creatures, each race as well adapted as its 
fellows to the circumstances in which it is placed. 

We are taught, then, yet another lesson. We see 
that, even though we could prove that every living 
creature on this earth would at once perish if removed 
to another orb, yet we cannot thence conclude that 
that orb is uninhabited. On the contrary, the lesson 
conveyed by our earth's analogy leads to the conclusion 



* Perhaps the fact that there are certain kinds of fish which cannot 
only live out of water, but can travel across the dry land, or climb trees, 
tdfords an even more striking instance of Nature's power of adapting 
creatures to the circumstances which surround them. 






32 OTHER WORLDS THAN OURS 

that many worlds may exist, abundantly supplied with 
living creatures of many different species, where yet 
every form of life upon our earth — bird, beast, or fish, 
reptile, insect, or animalcule — would perish in a few 
moments.* 

There remains yet a last lesson to be drawn from 
terrestrial analogies. On the earth there are regions 
where no form of life exists or can exist. Within the 
flaming crater of the volcano, or in the frozen heart of 
the iceberg, no living creature has its being. Yet even 
here Nature proves to us that the great end and aim 
of all her working is to afford scope and room for new 
forms of life, or to supply the wants of those which 
already exist. The volcano will die out, and the 
scene of its activity will one day become the abode of 
myriads of living creatures who would have perished 
in a moment in its consuming fires. The iceberg will 
melt, and its substance will once again be peopled with 
busy life. But this is little. It is the work of which 

* I might add, to the instances here cited, many others which seem 
even more striking. I have already referred to Dr. Carpenter's dis- 
covery, that in the depths of the Atlantic, where the pressure of the sea 
is so enormous that no ordinary instruments can resist its effects, where 
it had even been thought that no light can penetrate, there are myriads 
of living creatures having even organs of vision. We know, too, that in 
strong acids which would instantly kill bird, beast, fish, or insect placed 
within them, there exist and thrive minute creatures, adapted by Nature. 
to the strange conditions in which they are placed. Even in the bowels of 
the earth and in the very neighborhood of active volcanoes, we find the 
volcano-fish existing in such countless thousands, that, when they are 
from time to time vomited forth by the erupting mountain, their bodies 
are strewn over enormous regions, and, as they putrefy beneath the sun's 
rays, spread pestilence and disease among the inhabitants of the neigh- 
boring districts. 



WHAT OUR EARTH TEACHES US. 33 

volcano and iceberg are the signs, which most signifi- 
cantly teaches us what is Nature's real aim. Tho 
volcano is the index of those busy subterranean forces 
which are remodelling the earth's frame, slowly chan- 
ging the level of the land, making continents of oceans 
and oceans of continents, preserving and vivifying all 
things, while all things seem to suffer a gradual de- 
struction. The iceberg, too, has its work in remod- 
elling and fashioning the surface of new continents. 
But it exhibits also the action of Nature for the present 
benefit of the creatures which exist upon the earth. 
It acts an important part in the formation and main- 
tenance of the system of oceanic circulation on which 
the welfare of land creatures and water creatures so 
largely depends. And so of a multitude of other 
phenomena, which appear at first sight significant 
rather of the destructive than of the life-preserving 
character of Nature. The tornado and the thunder- 
storm, the earthquake and the volcano — nay, even the 
dreaded returns of plague and pestilence, have each a 
more powerful influence by far toward the preservation 
than they have toward the destruction of life. 

We see, then, that even when we can prove that an 
orb in space is so circumstanced that no life could by 
any possibility exist upon its surface; if it were the 
scene of a fierce and destructive turmoil, one moment 
of which would suffice to destroy every living creature 
now existing upon the earth ; if its whole mass were 
heated to a degree a thousandfold more intense than 
that of the fiercest heat we know of; if its surface were 
bound in a cold compared with which our arctic frosto 



34 



OTHER WORLDS THAN OURS. 



would seem like tropical heat ; or even if the most raj^id 
alternation of these extremes took place npon and 
within it ,- even then we could not conclude that the 
principal purpose for which the Almighty had created 
it had not been the support of life, either in long-past 
ages, or in ages yet to come. And lastly, though we 
could safely assert of any celestial object, that neither 
now, nor at any past or future time, could it serve as 
the abode of living creatures, yet we are led by 
terrestrial analogies to the conclusion that it has yet 
been created to support life in other ways. So that 
those very orbs, of which it seems safest to assert that 
they are, have ever been, and must ever remain un- 
inhabited, speak to us, no less strongly than those 
which appear best suited for habitation, of the exist- 
ence of other worlds than ourn. 



CHAPTER II. 

WHAT WE LEARN FROM THE SUN. 

I do not propose to dwell in this chapter on the views 
which have been propounded respecting the sun's 
habit ability. It is not merely that I regard those 
views as too hizarre and fanciful to fiud place in a 
serious consideration of the subject I am dealing with, 
nor that the progress of recent observation has rendered 
them utterly untenable, but that, in fact, they do not 
belong to what the sun teaches us. I wish to consider 
only the real evidence which the sun affords respecting 
the scheme of creation, to dwell upon the purposes 
which he subserves in the economy of the solar system, 
and thence to deduce a lesson respecting those other 
suns scattered throughout space, which we call the 
fixed stars. 

Let us first endeavor to form adequate conceptions 
respecting the dimensions of the great central luminary 
of the solar system. 

Let the reader consider a terrestrial globe three 
inches in diameter, and search out on that globe the 
tiny triangular speck which represents Great Britain. 
Then let him endeavor to picture the town in which 



36 OTHER WORLDS THAN OURS. 

he lives as represented by the minutest pin-mark that 
could possibly be made upon this speck. He will then 
have formed some conception, though but an inade- 
quate one, of the enormous dimensions of the earth's 
globe, compared with the scene in which his daily life 
is cast. JSTow, on the same scale, the sun would be rep- 
resented by a globe about twice the height of an ordi- 
nary sitting-room. A room about twenty-six feet in 
length, and height, and breadth, would be required to 
contain the representation of the sun's globe on this 
scale, while the globe representing the earth could be 
placed in a moderately large goblet. 

Such is the body which sways the motions of the 
solar system. The largest of his family, the giant 
Jupiter, though of dimensions which dwarf those of the 
earth or Yenus almost to nothingness, would yet only 
be represented by a thirty-two inch globe, on the scale 
which gives to the sun the enormous volume I have 
spoken of. Saturn would have a diameter of about 
twenty-eight inches, his ring measuring about five feet 
in its extreme span. Uranus and Neptune would be 
little more than a foot in diameter, and all the minor 
planets would be less than the three-inch earth. It 
will thus be seen that the sun is a worthy centre of the 
great scheme he sways, even when we merely regard 
his dimensions. 

The sun outweighs fully seven hundred and forty 
times the combined mass of all the planets whioh 
circle around him, so that, when we regard the energy 
of his attraction, we still find him a worthy ruler of 
the planetary scheme. 



WHAT WE LEARN FROM TEE SUN. 37 

But, after all, the enormous volume and mass of 
the sun form the least important of his characteristics 
as the ruling body of the solar system. It is when we 
contemplate him as the source whence the supplies 
of heat and light required by our own world and the 
other planets are plentifully bestowed, that we see 
what is his chief office in the economy of the planetary 
scheme. 

Properly speaking, the physical constitution of the 
sun only requires to be dealt with in such a work as 
the present in so far as it is directly associated with 
the sun's action upon the worlds around him, or as it 
may bear on the question of the constitution of those 
worlds. But the subject is so interesting, and it would 
indeed be so difficult to draw a line of demarcation 
between the facts which bear upon the question of 
other worlds and those which do not, that I may be 
permitted to enter at some length into a consideration 
of the solar orb, as modern physical discoveries pre- 
sent it to our contemplation. 

The study of solar physics may be said to have 
commenced with the discovery of the sun-spots, about 
two hundred and sixty years ago. These spots were 
presently found to traverse the solar disk in such a 
way as to indicate that the sun turns upon an axis 
once in about twenty-six days. Nor will this rotation 
appear slow, when we remember that it implies a mo- 
tion of the equatorial parts of the sun's surface at a 
rate exceeding some seventy times the motion of our 
swiftest express trains. 

Next came the discovery that the solar spots are not 



38 OTHER WORLDS THAN OURS. 

surface-stains, but deep cavities in the solar substance. 
The changes of appearance presented by the spots aa 
they traverse the solai disk led Dr. Wilson to form this 
theory so far back as 1779 ; but, strangely enough, it is 
only in comparatively recent times that the hypothesis 
has been finally established, since even within the last 
ten years a theory wa3 put forward which accounted 
satisfactorily for most of the changes of appearance 
observed in the spots, by supposing them to be due to 
solar clouds hanging suspended at a considerable ele- 
vation above the true photosphere. 

Sir "William Herschel, reasoning from terrestrial 
analogies, was led to look on the spot-cavities as ap- 
ertures through a double layer of clouds. He argued 
that, were the solar photosphere of any other nature, it 
would be past comprehension that vast openings should 
form in it, to remain open for months before they close 
up again. Whether we consider the enormous rapidity 
with which the spots form and with which their figure 
changes, or the length of time that many of them remain 
visible, we find ourselves alike perplexed, unless we 
assume that the solar photosphere resembles a bed of 
clouds. Through a stratum of terrestrial clouds open- 
ings may be formed by atmospheric disturbances, but 
while undisturbed the clouds will retain any form once 
impressed upon them, for a length of time correspond- 
ing to the weeks and months during which the solar 
spots enduie. 

And because the solar spots present two distinct 
varieties of light, the faint penumbra and the dark 
umbra or nucleus, Herschel saw the necessity of assum- 



WHAT WE LEARN FROM THE SUN. 39 

mg that there are two beds of clouds, the outer self- 
luminous and constituting the true solar photosphere, 
the inner reflecting the light received from the outer 
layer, and so shielding the real surface of the sun from 
the intense light and heat which it would otherwiso 
receive. 

But while recent discoveries have confirmed Sir 
William Her sch el's theory about the solar cloud- 
envelopes, they have by no means given countenance 
to his view that the body of the sun may possibly be 
cool. The darkness of the nucleus of a spot is found, 
on the contrary, to give proof that in that neighbor- 
hood the sun is hotter, because it parts less readily 
with its heat. We shall see presently how this is. 
Meantime let it be noticed, in passing, that a close 
scrutiny of large solar spots has revealed the existence 
of an intensely black spot in the midst of the umbra. 
This black spot must be regarded as the true nucleus. 

The circumstance that the spots appear only on two 
bands of the sun's globe, corresponding to the sub- 
tropical zones on our own earth, led the younger 
Herschel to conclusions as important as those which 
his father had formed. He reasoned, like his father, 
from terrestrial analogies. On our own earth the sub- 
tropical zones are the regions where the great cyclonic 
storms have their birth, and rage with their chief fury. 
Here, therefore, we have the analogue of the solar 
spots, if only we can show reason for believing that 
any causes resembling those which generate the 
terrestrial cyclone operate upon those regions of the 
sun where the solar spots make their appearance. 



40 



OTHER WORLDS THAN OURS. 



We know that the cyclone is due to the excess of 
heat at the earth's equator. It is true that this ex- 
cess of heat is always in operation, whereas cyclones 
are not perpetually raging in sub-tropical climates. 
Ordinarily, therefore, the excess of heat does not 
cause tornadoes. Certain aerial currents are generated, 
whose uniform motion suffices, as .a rule, to adjust the 
conditions which the excess of heat at the equator 
would otherwise tend to disturb. But when through 
any cause the uniform action of the aerial currents is 
either interfered with, or is insufficient to maintain 
equilibrium, then cyclonic or whirling motions are 
generated in the disturbed atmosphere, and propagated 
over a wide area of the earth's surface. 

Now we recognize the reason of the excess of heat 
at the earth's equator, in the fact that the sun shines 
more directly upon that part of the earth than on the 
zones which lie in higher latitudes. Can we find any 
reason for suspecting that the sun, which is not heated 
from without as the earth is, should exhibit a similar 
peculiarity ? Sir John Herschel considers that we 
can. If the sun has an atmosphere extending to a 
considerable distance from his surface, then there can 
be little doubt that, owing to his rotation upon his 
axis, this atmosphere would assume the figure of an 
oblate spheroid, and would be deepest over the solar 
equator. Here, then, more of the sun's heat would 
be retained than at the poles, where the atmosphere 
is shallowest. Thus, that excess of heat at the solar 
equator which is necessary to complete the analogy 



WHAT WE LEARN FROM THE SUN. 41 

between the sun-spots and terrestrial cyclones, seems 
satisfactorily established. 

It must be remarked, however, that this reasoning, 
so far as the excess of heat at the sun's equator is con- 
cerned, only removes the difficulty a step. If there 
were indeed an increased depth of atmosphere over the 
sun's equator sufficing to retain the requisite excess of 
heat, then the amount of heat we receive from the 
sun's equatorial regions ought to be appreciably less 
than the amount emitted from the remaining portions 
of the solar surface. This is not found to be the case, 
so that, either there is no such excess of absorption, or 
else the solar equator gives out more heat, in other 
words, is essentially hotter, than the rest of the sun. 
But this is just the peculiarity of which we want the 
interpretation. 

It may be taken for granted, however, that there 
is an analogy between the sun-spots and terrestrial 
cyclonic storms, though as yet we are not very well 
able to understand its nature. 

Then next we come to one of the most interesting 
discoveries ever made respecting the sun — the discovery 
that the spots increase and diminish in frequency in 
a periodic manner. We owe this discovery to the 
laborious and systematic observations made by Herr 
Schwabe, of Dessau. In these pages any account of 
his work would be out of place. We need only dwell 
upon the result, and upon other discoveries which have 
been made by observers who have taken up the same 
work. 

Schwabe found in the course of about ten and a 



£ 2 OTHER WORLDS THAN OURS. 

half years, the solar spots pass through a complete 
cycle of changes. They become gradually more aud 
more numerous up to a certain maximum, and then 
as gradually diminish. At length the sun's face be- 
comes not only clear of spots, but a certain well- 
marked darkening around the border of his disk disap- 
pears altogether for a brief season. At this time the 
sun presents a perfectly-uniform disk. Then gradually 
the spots return, become more and more numerous, 
and so the cycle of changes is run through again. 

The astronomers who have watched the sun from 
the Kew Observatory have found that the process of 
change by which the spots sweep in a sort of " wave 
of increase " over the solar disk is marked by several 
minor variations. As the surface of a great sea-wave 
will be traversed by small ripples, so the gradual in- 
crease and diminution in the number of the solar spots 
are characterized by minor gradations of change, which 
are sufficiently well marked to be distinctly cognizable. 

There seems every reason for believing that the 
periodic changes thus noticed are due to the influence 
of the planets upon the solar photosphere, though in 
what way that influence is exerted is not at present 
perfectly clear. Some have thought that the mere 
attraction of the planets tends to produce tides of 
some sort in the solar envelopes. Then, since the 
height of a tide so produced varies as the cube or 
third power of the distance, it has been thought that 
a planet when in perihelion would generate a much 
larger solar tide than when in aphelion. So that, as 
Jupiter has a period nearly equal to the sun-spot pe- 



WHAT WE LEARN FROM THE SUN. 43 

riod, it lias been supposed that the attractions of this 
planet are sufficient to account for the great spot-pe- 
riod. Venus, Mercury, the Earth, and Saturn have, 
in a similar manner, been rendered accountable for 
the shorter and less distinctly marked periods. 

"Without denying that the planets may be, and prob- 
ably are; the bodies to whose influence the solar-spot 
periods are to be ascribed, I yet venture to express 
very strong doubts whether the attraction of Jupiter 
is so much greater in perihelion than in aphelion as 
to account for the fact that whereas at one season 
the face of the sun shows many spots, at another it is 
wholly free from them.* 

However, we are not at present concerned so much 
with the explanation of facts as with the facts them- 
selves. We have to consider rather what the sun is 
and what he does for the solar system, than why these 
things are so. 

Let us note, before passing to other circumstances 
of interest connected with the sun, that the variable 
condition of his photosphere must cause him to change 
in brilliancy as seen from vast distances. If Herr 
Schwabe, for instance, instead of observing the sun's 
spots from his watch-tower at Dessau, could have re- 
moved himself to a distance so enormous that the 
sun's disk would have been reduced, even in the most 
powerful telescope, to a mere point of light, there can 

* Recently Prof. Kirkwood has published a most interesting series of 
inquiries, going far to prove that the real secret of the planetary influ- 
ences lies in the fact that the sun's surface is not uniform, and that 
on a certain solar longitude the planetary influences are more effective 
than elsewhere. 



H 



OTHER WORLDS THAN OURS. 



be no doubt that the only effect which he would have 
been able to perceive would have been a gradual in- 
crease and diminution of brightness, having a period 
of about ten and a half years. 

Our sun, therefore, viewed from the neighbor- 
hood of any of the stars, whence undoubtedly he would 
simply appear as one among many fixed stars, would 
be a " variable," having a period of ten and a half 
years. And further, if an observer, viewing the sun 
from so enormous a distance, had the means of very 
accurately measuring its light, he would undoubtedly 
discover that, while the chief variation of the sun takes 
place in a period of ten and a half years, its light is 
subjected to minor variations, having shorter periods. 

The discovery that the periodic changes of the 
sun's appearance are associated with the periodic 
changes in the character of the earth's magnetism is 
the next that we have to consider. 

It had long been noticed that, during the course 
of a single day, the magnetic needle exhibits a minute 
change of direction, taking place in an oscillatory 
manner. And, when the character of this vibration 
came to be carefully examined, it was found to corre- 
spond to a sort of effort on the needle's part to turn 
towar,d the sun. For example, when the sun is on 
the magnetic meridian, the needle has its mean posi- 
tion. This happens twice in the day, once when the 
sun is above the horizon, and once when he is below it. 
Again, when the sun is midway between these two 
positions — which also happens twice in the day — the 
needle has its mean position, because the northern and 



WHAT WE LEARN FROM THE SUN. 4.5 

the southern ends make equal efforts (so to speak) to 
direct themselves toward the sun. Four times in the 
day, then, the needle has its mean position, or is di- 
rected toward the magnetic meridian. But, when the 
sun is not in one of the four positions considered, that 
end of the needle which is nearest to him is slightly 
turned away from its mean position, toward him. 
The change of position is very minute, and only the 
exact modes of observation made use of in the present 
age would have sufficed to reveal it. There it is, 
however, and this minute and seemingly unimportant 
peculiarity has been found to be full of meaning. 

Had science merely measured this minute variation, 
the work would have given striking evidence of the 
exact spirit in which men of our day deal with natural 
phenomena. But science was to do much more. The 
variations of this minute variation were to be inquired 
into ; their period was to be searched for ; the laws by 
which they were regulated and by which their period 
might perhaps itself be rendered variable, were to be 
examined ; and, finally, their relation to other natural 
laws was to be sought after. That Science should set 
herself to an inquiry so delicate and so difficult, in a 
spirit so exacting, was nothing unusual. It is thus that 
all the great discoveries of our day have been effected. 
But it is well that the reader should recognize the 
careful scrutiny to which natural phenomena have 
been subjected before the great laws we have to con- 
sider were made known. It is thought by many, who 
have not been at the pains to examine what Science is 
really doing in our day, that the wonders she presents 



*.6 OTHER WORLDS THAN OURS. 

to men's contemplation, the startling revelations which 
are being made from day to day, are merely dreams 
and fancies, which replace indeed the dreams and 
fancies of old times, bnt have no worthier claims on 
our belief. Those who carefully examine the history 
of science will be forced to adopt a very different 
opinion. 

The minute vibrations of the magnetic needle, thus 
carefully watched — day after day, month after month, 
year after year — were found to exhibit a yet more 
minute oscillatory change. They waxed and waned 
within narrow limits of variation, but yet in a manner 
there was no mistaking. The period of this oscillatory 
change was not to be determined, however, by the ob- 
servations of a few years.* Between the time when 
the diurnal vibration was least until it had reached its 
greatest extent, and thence returned to its first value, 
no less than ten and a half years elapsed, and a much 
longer time passed before the periodic character of the 
change was satisfactorily determined. 

The reader will at once see what these observations 
tend to. The sun-spots vary in frequency within a 
period of ten and a half years, and the magnetic diur- 
nal vibrations vary within a period of the same du- 
ration. It might seem fanciful to associate the two 

* The reader must not understand that the account here given 
presents in any sense even a general view of the labors of those who 
have studied the earth's magnetism. I touch only on those points by 
which the association between the earth's magnetism and the physical 
condition of the sun is most clearly indicated ; because these points 
alone bear on the subject of this chapter. Hew they do so will appear 
further on. 



WHAT WE LEARN FROM TEE SUN +7 

periodic series of changes together, and doubtless when 
the idea first occurred to Lamont, it was not with any 
great expectation of finding it confirmed, that he ex- 
amined the evidence bearing on the point. Judging 
from known facts, we may see reasons for such an 
expectation in the correspondence of the needle's 
diurnal vibration with the sun's apparent motion, and 
the law which has been found to associate the annual 
variations of the magnet's power with the sun's dis- 
tance. But undoubtedly when the idea occurred to 
Lamont, it was an exceedingly bold one, and the 
ridicule with which the first announcement of the sup- 
posed law was received, even in scientific circles, suf- 
fices to show how unexpected that relation was, which 
is now so thoroughly established. For a careful com- 
parison between the two periods has demonstrated that 
they agree most perfectly, not merely in length, but 
maximum for maximum, and minimum for minimum. 
When the sun-spots are most numerous, then the daily 
vibration of the magnet is most extensive, while, when 
the sun's face is clear of spots, the needle vibrates 
over its smallest diurnal arc. 

Then the intensity of the magnetic action has been 
found to depend upon solar influences. The vibra- 
tions by which the needle indicates the progress of 
those strange disturbances of the terrestrial magnetism 
which are known as magnetic storms, have been found 
not merely to be most frequent when the sun's face 
is most spotted, but to occur simultaneously with the 
appearance of signs of disturbance in the solar pho- 
tosphere. For instance, during the autumn of 1859, 



j.8 OTHER WORLDS THAN OURS. 

-the eminent solar observer, Carrington, noticed the 
apparition of a bright spot upon the sun's surface. 
The light of this spot was so intense, that he ima- 
gined the dark glass which protected his eye had been 
broken. By a fortunate coincidence, another observer, 
Mr. Hodgson, happened to be watching the sun at the 
game instant, and witnessed the same remarkable 
appearance. Now it was found that the self-register- 
ing magnetic instruments of the Kew Observatory had 
been sharply disturbed at the instant when the bright 
spot was seen. And afterward it was learned that the 
phenomena which indicate the progress of a magnet- 
ic storm had been observed in many places. Tele- 
graphic communication was interrupted, and, in some 
cases, telegraphic offices were set on fire ; auroras 
appeared both in the northern and southern hemi- 
sphere during the night which followed ; and the 
whole frame of the earth seemed to thrill responsively 
to the disturbance which had affected the great cen- 
tral luminary of the solar system. 

The reader will now see why I have discussed re- 
lations which hitherto he may perhaps have thought 
very little connected with my subject. He sees that 
there is a bond of sympathy between our earth and the 
sun ; that no disturbance can affect the solar photo- 
sphere, without affecting our earth to a greater or less 
degree. But if our earth, then also the other planets. 
Mercury and Yenus, so much nearer the sun than we 
are, surely respond even more swiftly and more dis- 
tinctly to the solar magnetic influences. But beyond 
our earth, and beyond the orbit of moonless Mars, the 



WHAT WE LEARN FROM THE SUN. ^ 

magnetic impulses speed with the Telocity of light. 
The vast globe of Jupiter is thrilled from pole to pole 
as the magnetic wave rolls in upon it ; then Saturn 
feels the shock, and then the vast distances beyond 
which lie Uranus and Neptune are swept by the ever- 
lessening yet ever-widening disturbance-wave. "Who 
shall say what outer planets it then seeks ? or who, 
looking back upon the course over which it has trav- 
elled, shall say that planets alone have felt its effects ? 
Meteoric and cometic systems have been visited by the 
great magnetic wave, and upon the dispersed mem- 
bers of the one and the subtle structure of the other 
effects even more important may have been produced 
than those striking phenomena which characterize the 
progress of the terrestrial or planetary magnetic 
storms. 

When we remember that what is true of a rela- 
tively great solar disturbance, such as the one wit- 
nessed by Messrs. Carrington and Hodgson, is true also 
(however different in degree) of the magnetic influ- 
ences which the sun is at every instant exerting, we 
see that a new and most important bond of union ex- 
ists between the members of the solar family. The 
sun not only sways them by the vast attraction of his 
gravity, not only illumines them, not only warms them, 
but he pours forth on all his subtle yet powerful mag- 
netic influences. A new analogy between the mem- 
bers of the solar system is thus introduced, to reenforce 
those other analogies which have been held so strik- 
ingly to indicate that the ends for which our earth has 

been created are not different from those which the 
4 



5 OTHER WORLDS THAN OURS. 

Creator had in view when He planned the other mem- 
bers of the solar system.* 

And now we pass on to other discoveries, bearing at 
once and with equal force upon the relations between 
the various members of the solar scheme and upon the 
position which that scheme occupies in the universe. 

Hitherto we have been considering the teachings ol 
the telescope ; we have now to consider what we have 
learned by means of an instrument of yet higher 
powers. As I shall have to refer very frequently, 
throughout this volume, to the teachings of the spec- 
troscope, it will be well that I should briefly describe 
what it is that this instrument really effects. Were I 
simply to state the results of its use, without describing 
its real character, many of my readers would be dis- 
posed to believe that astronomers are as credulous as 
in reality they are exacting and scrupulous, where new 
facts and observations are in question. 

The real end and aim of the telescope, as applied by 
the astronomer to the examination of the celestial ob- 
jects, is to gather together the light which streams from 
each luminous point throughout space. We may re- 
gard the space which surrounds us on every side as an 

* I must remark here, once for all, that in speaking of the plans of 
the Creator, of His mode of working, or of the laws which He has estab- 
lished, I by no means intend such words to be taken literally. For 
want of better, such words as these must be employed in speaking of the 
relations between Almighty God and His universe. But in truth these 
relations are as inconceivable by us as infinity of space or infinity of 
time. We know that they exist, as certainly as we know that space and 
time are both infinite, but human language can no more indicate their 
nature than it can present to the mind an adequate picture of space of 
Lime 



WHAT WE LEARN FROM THE SUN. ^ 

ocean without bounds or limits, an ocean across which 
there are ever sweeping waves of light, either emitted 
directly from the various bodies subsisting throughout 
space, or else reflected from their surfaces. Other 
forms of wave also speed across those limitless depths 
in all directions, but the light-waves are those which 
at present concern us. Our earth is as a minute 
island placed within the ocean of space, and to the 
shores of this tiny isle the light- waves bear their mes- 
sage from the orbs which lie like other isles amid the 
fathomless depths around us. With the telescope the 
astronomer gathers together portions of light-waves 
which else would have travelled in diverging directions. 
By thus intensifying their action, he enables the eye 
to become cognizant of their trie nature. Precisely as 
the narrow channels around our shores cause the tidal 
wave, which sweeps across the open ocean in almost 
insensible undulations, to rise and fall through a wide 
range of variation, so the telescope renders sensible 
the existence of light-waves which would escape the 
notice of the unaided eye. 

The telescope, then, is essentially a light-gatherer. 

The spectroscope is used for another purpose. It 
might be called the light-sifter. It is applied by the 
astronomer to analyze the light which comes to him 
from beyond the ocean of space, and so to enable him 
to learn the character of the orbs from which that 
Light proceeds. 

The principle of the instrument is simple, though 
the appliances by which its full powers can alone be 
educed are somewhat complicated. 



$2 OTHER WORLDS THAN OURS. 

A ray of sunlight falling on a prism of glass 01 
crystal does not emerge unchanged in character. Dif- 
ferent portions of the ray are differently bent, so 
that when they emerge from the prism they no longer 
travel side by side as before. The violet part of the 
light is bent most, the red least; the various colors 
from violet through blue, green, and yellow, to red, 
being bent gradually less and less. 

The prism then sorts , or sifts, the light-waves. 

But we want the means of sifting the light-waves 
more thoroughly. The reader must bear with me while 
I describe, as exactly as possible in the brief space 
available to me, the way in which, the first rough work 
of the prism has been modified into the delicate and 
gignificant work of the spectroscope. It is well worth 
while to form clear views on this point, because so 
many of the wonders of modern science are associated 
with spectroscopic analysis. 

If, through a small round hole in a shutter, light 
is admitted into a darkened room, and a prism be 
placed with its refracting angle downward and hori- 
zontal, a vertical spectrum, having its violet end up- 
permost, will be formed on a screen suitably placed to 
receive it. 

But now let us consider what this spectrum really is. 
If we take the light- waves corresponding to any partic- 
ular color, we know, from optical considerations, that 
these waves emerge from the prism in a pencil exactly 
resembling in shape the pencil of white light which falls 
on the prism. They therefore form a small circular or 
oval image on their own proper part of the spectrum 



WHAT WE LEARN FROM THE SUN. 



S3 



Hence the spectrum is in reality formed of a multi- 
tude of overlapping images, varying in color from vio- 
let to red, It thus appears as a rainbow-tinted streak, 
presenting every gradation of color between the utmost 
limits of visibility at the violet and red extremities. 

If we had a square aperture to admit the light, we 
should get a similar result. If the aperture were ob- 
long, there would still be overlapping images ; but if 
the length of the oblong were horizontal, then, since 
each image would also be a horizontally-placed oblong, 
the overlapping would be less than when the images 
were square. Suppose we diminish the overlapping as 
much as possible ; in other words, suppose we make the 
oblong slit as narrow as possible ? Then, unless there 
were in reality an infinite number of images distributed 
all along the spectrum from top^to bottom, the images 
might be so narrowed as not to overlap ; in which case, 
of course, there would be horizontal dark spaces or gaps 
in our spectrum. Or, again, if we failed in finding gaps 
of this sort by simply narrowing the aperture, we might 
lengthen the spectrum by increasing the refracting an- 
gle of the prism, or by using several prisms, and so on. 

The first great discovery in solar physics, by means 
of the analysis of the prism (though the discovery had 
little meaning at the time), consisted in the recognition 
of the fact that, by means of such devices as the above, 
dark gaps or cross-lines can be seen in the solar spec- 
trum. In other words, light- waves of the various gra- 
dations corresponding to all the tints of the spectrum 
from violet to red, do not travel to us from the great 
central luminary of our system. Eemembering that 



^ 4 OTHER WORLDS THAN OURS. 

the effect we call color is due to the length of the light- 
waves, the effect of red corresponding to light-waves 
of the greatest length, while the effect of violet corre- 
sponds to the shortest light-waves, we see that in effect 
the sun sends forth to the worlds which circle around 
him light-waves of many different lengths, but not of 
all. Of so complex and interesting a nature is ordi- 
nary daylight. 

But spectroscopists sought to interpret these dark 
lines in the solar spectrum, and it was in carrying out 
this inquiry — which even to themselves seemed almost 
hopeless, and to many would appear an utter waste of 
time — that they lighted upon the noblest method of 
research yet revealed to man. 

They examined the spectra of the light from incan- 
descent substances (white-hot metals and the like), and 
found that in these spectra there are no dark lines. 

They examined the spectra of the light from the 
stars, and found that these spectra are crossed by dark 
lines resembling those in the solar spectrum, but dif- 
ferently arranged. 

They tried the spectra of glowing vapors, and they 
obtained a perplexing result. Instead of a number of 
dark lines across a rainbow-tinted streak, they found 
bright lines of various color. Some gases would give 
a few such lines, others many, some only one or two. 

Then they tried the spectrum of the electric spark, 
and they found here also a series of bright lines, but 
not always the same series. The spectrum varied ac- 
cording to the substances between which the spark 
was taken, and the medium through which it passed. 



WHAT WE LEARN FROM THE SUN. 55 

Lastly, they found that the light from an incan- 
descent solid or liquid, when shining through various 
vapors, no longer gives a spectrum without dark lines, 
but that the dark lines which then appear vary in 
position, according to the nature of the vapor through 
which the light has passed. 

Here were a number of strange facts, seemingly too 
discordant and too perplexing to admit of being inter- 
preted. Yet one discovery only was wanting to bring 
them all into unison. 

In 1859, Kirchhoff, while engaged in observing the 
solar spectrum, lighted on the discovery that a certain 
double dark line, which had already been found to 
correspond exactly in position with the double bright 
line forming the spectrum of the glowing vapor of 
sodium, was intensified, when the light of the sun was 
allowed to pass through that vapor. This at once 
suggested the idea, that the presence of this dark line 
(or rather, pair of dark lines) in the spectrum of the 
sun is due to the existence of the vapor of sodium in 
the solar atmosphere, and that this vapor has the power 
of absorbing the same order of light-waves as it emits. 
It would of course follow from this, that the other 
dark lines in the solar spectrum are due to the pres- 
ence of other absorbent vapors in its atmosphere, and 
that the identity of these would admit of being est ab- 
ashed in the same way, supposing this general law to 
hold, that a vapor emits the same light-waves that it 
is capable of absorbing. 

Kirchhoff was soon able to confirm his views by a 
variety of experiments. The general principles to 



5 6 OTHER WORLDS THAN OURS. 

wliicli liis researches led — in other words, the princi- 
ples which form the basis of spectrum-analysis — are as 
follows : 

1. An incandescent solid or liquid gives a con- 
tinuous spectrum. 

2. A glowing vapor gives a spectrum of white 
lines, each vapor having its own set of bright lines, 
so that, from the appearance of a bright- line spectrum, 
one can tell the nature of the vapor or vapors whose 
light forms the spectrum. 

3. An incandescent solid or liquid shining through 
absorbent vapors gives a rainbow-tinted spectrum 
crossed by dark lines, these dark lines having the 
same position as the bright lines belonging to the 
spectra of the vapors ; so that, from the arrangement 
of the dark lines in such a spectrum, one can tell the 
nature of the vapor or vapors which surround the 
source of light.* 

* To these may be added the following laws : 

4. Light reflected from any opaque body gives the same spectrum as 
it would have given before reflection. 

5. But if the opaque body be surrounded by vapors, the dark lines 
corresponding to these vapors make their appearance in the spectrum 
with a distinctness proportioned to the extent to which the light has 
penetrated those vapors before being reflected to us. 

6. If the reflecting body be itself luminous, the spectrum belonging 
to it is superadded to the spectrum belonging to the reflected light. 

7. Glowing vapors surrounding an incandescent source of light may 
cause bright lines or dark lines to appear in the spectrum, according as 
they are more or less heated ; or they may emit just so much ligh t as to 
make up for what they absorb, in which case there will remain no trace 
of their presence. 

8. The electric spark presents a bright-line spectrum, compounded 
of the spectra belonging to the vapors of those substances between which, 
and of those through which, the discharge takes place. According to 






WHAT WE LEARN FROM THE SUN. 57 

Tlie application of the new method of research to 
the study of the solar spectrum quickly led to a number 
of most interesting discoveries. It was found that ; 
besides sodium, the sun's atmosphere contains the va- 
pors of iron, calcium, magnesium, chromium, and 
other metals. The dark lines corresponding to these 
elements appear unmistakably in the solar spectrum. 
There are other metals, such as copper and zinc, which 
seem to exist in the sun, though some of the corre- 
sponding dark lines have not yet been recognized. As 
yet it has not been proved that gold, silver, mercury, 
tin. lead, arsenic, antimony, or aluminium, exist in 
the sun — though we can by no means conclude, nor 
indeed is it at all probable, that they are absent from 
his substance. The dark lines belonging to hydrogen 
are very well marked indeed in the solar spectrum, and, 
as we shall see presently, the study of these lines has 
afforded most interesting information respecting the 
physical constitution of the sun. 

Now we notice at once how importantly these 
researches into the sun's structure bear upon the sub- 
ject of this treatise. It would be indeed interesting 
to consider the actual condition of the central orb of 
the planetary scheme, to picture in imagination the 
metallic oceans which exist upon his surface, the con- 
tinual evaporation from those oceans, the formation of 
metallic clouds, and the downpour of metallic showers 

the nature of these vapors and of the discharge itself, the relative inten- 
sity of the component parts of the spectrum will be variable. 

Lastly, the appearance of the spectrum belonging to any element 
will vary according to the circumstances of pressure and temperature 
under which the element may emit light. 



$8 OTHER WORLDS THAN OURS. 

upon the surface of the sun. But apart from such 
considerations, and viewing Kirchhoff's discoveries 
simply in their relation to the subject of other worlds, 
we have enough to occupy our attention. 

If it could have been shown that, in all probabil- 
ity, the substance of the sun consists of materials 
wholly different from those which exist in this earth, 
the conclusion obviously to be drawn from such a 
discovery would be that the other planets also are 
differently constituted. We could not find any just 
reason for believing that in Jupiter or Mars there ex- 
ist the elements with which we are acquainted, when 
we found that even the central orb of the planetary 
system exhibits no such feature of resemblance to the 
earth. But now that we know, quite certainly, that 
the familiar elements iron, sodium, and calcium, exist 
in the sun's substance, while we are led to believe with 
almost perfect assurance that all the elements we are 
acquainted with also exist there, we see at once that, 
in all probability, the other planets are constituted 
in the same way. There may of course be special 
differences: in one planet the proportionate distribu- 
tion of the elements may differ, and even differ very 
markedly, from that which prevails in some other 
planet. But the general conclusion remains that the 
planets are formed of the elements which have so long 
been known as terrestrial; for we cannot recognize 
any reason for believing that our earth alone, of all 
the orbs which circle around the sun, resembles that 
great central orb in general constitution.* 

* It will be seen, in the chapter on Meteors and Comets, that thia 



WHAT WE LEARN FROM THE SUN. $g 

!N"ow, we have in this general law a means of passing 
beyond the bounds of the solar system, and forming no 
indistinct conceptions as to the existence and character 
of worlds circling around other suns. For it will be 
seen, in the chapter on the stars, that these orbs, like 
our sun, contain in their substance many of the so- 
called terrestrial elements, while it may not unsafely 
be asserted that all, or nearly all, those elements, and 
few or no elements unknown to us, exist in the sub- 
stance of every single star that shines upon us from the 
celestial concave. Hence we conclude that around 
those suns also there circle orbs constituted like them- 
selves, and therefore containing the elements with 
which we are familiar. And the mind is immediately 
led to speculate on the uses which those elements are 
intended to subserve. If iron, for example, is present 
in some noble orb circling around Sirius, we speculate 
not unreasonably respecting the existence on that orb 
— either now or in the past, or at some future time — 
of beings capable of applying that metal to the useful 
purposes which man makes it subserve. The imagi- 
nation suggests immediately the existence of arts and 
sciences, trades and manufactures, on that distant 
world. We know how intimately the use of iron has 
been associated with the progress of human civiliza- 
tion, and though we must ever remain in ignorance 
of the actual condition of intelligent beings in other 
worlds, we are yet led, by the mere presence of an 
element which is so closely related to the wants of 

conclusion has a most important bearing on the views we are to form 
respecting the original formation of the planetary scheme. 



60 OTHER WORLDS THAN OURS. 

man, to believe, with a new confidence, that for such 
beings those worlds must in truth have been fash- 
ioned. 

I would fain dwell longer on the thoughts sug- 
gested by the researches of Kirchhoff. Gladly too 
would I enter at length on an account of those inter- 
esting discoveries which have been made in connection 
with the last two total eclipses of the sun. The re- 
quirements of space, however, and some doubt as to 
the direct bearing of the last-named discoveries on the 
subject I have in hand, warn me to forbear. One 
point, however, remains, which is too intimately con- 
nected with my subject to be passed over. 

I refer to the sun's corona. 

It has been proved that the solar prominences con- 
sist of glowing vapors, hydrogen being their chief 
constituent. It has been found also, by comparing 
Mr. Lockyer's observations of the prominence-spectra 
with Dr. Frankland's elaborate researches into the 
peculiarities presented by the spectrum of hydrogen 
at different pressures, that even in the very neigh- 
borhood of the solar photosphere, these vapors prob- 
ably exist at a pressure so moderate as to indicate 
that the limits of the sun's vaporous envelope can- 
not lie very far (relatively) from the outer solar cloud- 
layer. 

Now, the solar corona has been seen, during total 
eclipses of the sun, to extend to a distance at least 
equal to the sun's diameter from the eclipsed orb. So 
that, assuming the corona to be a solar atmosphere, it 
would have a depth of about eight hundred and fifty 



WHAT WE LEARN FROM THE SUN 61 

thousand miles, and being also drawn toward the sun 
by his enormous attractive energy (exceeding more 
than twenty-seven times that of the earth), it could 
not fail to exert a pressure on his surface exceeding 
many thousand fold that of our air upon the earth. 
In fact, such an atmosphere, let its outermost layers 
be as rare as we can conceive, would yet have its 
lower layers absolutely liquefied, if not solidified, by 
the enormous pressure to which they would be sub- 
jected. We cannot, then, believe this. corona to be a 
solar atmosphere. 

Yet it is quite impossible to dissociate the corona, 
either wholly or in part, from the sun. I am aware 
that physicists of eminence have attempted to do this, 
and not only so, but to make of the zodiacal light a 
terrestrial phenomenon. But they have overlooked 
considerations which oppose themselves irresistibly to 
such a conclusion. 

In the first place, the mere fact that, during a 
total eclipse, the moon looks black, in the very heart 
of the corona, affords, when properly understood, the 
most conclusive evidence that the light of the corona 
comes from behind the moon. If the glare of our 
atmosphere could by any possibility account for the 
corona (which is not the case), then that glare should 
appear over the moon's disk also. That this is so is 
proved by the fact that, when the glare really does 
cover the moon, as while the sun is but slightly 
eclipsed, the moon is not projected as a black disk on 
the background of the sky, though, where her outline 
crosses the sun, it appears black, by contrast with the 



62 OTHER WORLDS THAN OURS. 

intensity of his light.* The point seems, however, 
too obvious to need discussion. 

And, secondly, as Mr. Baxendell has pointed out, 
during totality the part of the earth's atmosphere 
between the eye and the corona is not illuminated by 
the sun. Over a wide space all round the sun we are 
looking through an atmosphere which is completely 
dark. Infact, if the earth's atmosphere alone were 
in questiou, we ought to see a dark or negative co- 
rona around the sun, the illuminated atmosphere only 
beginning to be faintly visible at a considerable angu- 
lar distance from the sun. This argument, rightly 
understood, is altogether decisive of the question.f 

* It is also shown most conclusively, by a photograph of the eclipse 
of August, 1868, taken an instant before the totality. Here we see the 
glare trenching upon the moon's disk (elsewhere black), as it should 
theoretically. So soon as totality commenced, the glare had reached the 
moon's limb, whence it must immediateiy have passed quickly away. 

f In fact, if we take the mode of reasoning by which Mr. Lockyer 
has endeavored to get over certain physical difficulties presently to be 
mentioned, we shall be able to point definitely to the place where his 
argument fails. He says, conceive a tiny moon placed so as to appear 
coincident with the centre of the sun's disk. There will be atmospheric 
glare as well as direct sunlight. Now, conceive this small moon to 
expand until it all but covers the sun. Still there will be glare and a 
certain small proportion of direct sunlight. So far his reasoning is 
most just. But when he allows his expanding moon to cover tbe sun, 
and to extend beyond the solar disk as in total eclipse, the atmospheric 
glare can no longer be assumed to exist all round the expanding moon : 
at the moment when the moon just hides the sun, the glare begins to 
leave the moon, a gradually-expanding black ring being formed round 
that body. It is only necessary to consider where the glare comes from 
to see that this must be so. 

I have taken no account of diffraction here, because it has been 
abundantly proved that no corona of appreciable width could be formed 
around the moon during total eclipse by the diffraction of the rays of 
light as they pass near the moon's limb. 



WHAT WE LEARN FROM THE SUN. 63 

But the spectroscope lias given certain very per- 
plexing evidence respecting the light of the corona, 
and it remains that we should endeavor to see how 
that evidence bears on the interesting problem which 
the corona presents to our consideration. 

During the total eclipse of last August the Ameri- 
can observers found that the spectrum of the corona 
is continuous, but crossed by certain bright lines. If 
we accept the absence of dark lines as established by 
the evidence (which is doubtful), this result seems at 
first sight very difficult to explain. Referring to the 
principles of spectroscopic analysis stated at pp. 56, 57, 
it will be seen that we should be led to infer that the 
corona consists of incandescent matter surrounded by 
certain glowing gases. It is difficult to suppose that 
this is the real explanation of the phenomenon. 

Mr. Lockyer suggests that, if the corona shone by 
reflecting the solar light, the continuous spectrum 
might be accounted for by supposing the light from 
the glowing vapors around the sun to supply the 
part wanting where the solar dark lines are, and that 
some of these vapors shining yet more brightly would 
exhibit their bright lines upon the continuous back- 
ground of the spectrum. This view, as applied by 
Mr. Lockyer to the theory that the corona is a 
terrestrial phenomenon, is untenable, for the reasons 
already adduced. But, independently of those reasons, 
there are others which render such a solution of the 
difficulty unavailable. 

E"ow_, remembering that we have two established 
facts for our guidance, — (i.) the fact that the corona 



54 OTHER WORLDS THAN OURS. 

cannot be a solar atmosphere, and (ii.) the fact that it 
must be a solar appendage — I think a way may be 
found toward a satisfactory explanation. 

Let it be premised that the bright lines of the 
coronal spectrum correspond in position to those seen 
in the spectrum of the aurora, and that the same lines 
are seen in the spectrum of the zodiacal light, and in 
that of the phosphorescent light occasionally seen over 
the heavens at night. 

Since we have every reason to believe that the light 
of the aurora is due to electrical discharges taking 
place in the tipper regions of the air, we are invited to 
the belief that the coronal light may be due to similar 
discharges taking place between the particles (of what- 
ever nature) constituting the corona. 

Now, though the appearance of an aurora is due 
to some special terrestrial action (however excited), yet 
the material substances between which the discharges 
take place must be assumed to be at all times present 
in the upper regions of air. In all probability, they 
are the particles of those meteors which the earth 
is continually encountering. And since we know that 
meteor-systems must be aggregated in far greater 
numbers near the sun than near the earth, we may 
regard the coronal light as due to electrical dis- 
charges excited by the sun's action, and taking place 
between the members of such systems. Besides this 
light, however, there must necessarily be a large pro- 
portion of light reflected from these meteoric bodies. 
In this way the peculiar character of the coronal 
spectrum may be readily accounted for. We know, 



WHAT WE LEAR'S FROM THE SUN. 



65 



from the auroral spectrum, that the principal bright 
lines due to the electrical discharges would be precisely 
where we see bright lines in the coronal spectrum, 
But, besides these, there would be fainter bright lines 
corresponding to the various elements which exist iii 
the meteoric masses. These elements, we know, are 
the same as those in the substance of the sun. Thus 
the bright lines would correspond in position with the 
dark lines of the solar spectrum. Hence, as light re- 
flected by the meteors would give the ordinary solar 
spectrum, there would result from the combination a 
continuous spectrum, on which the bright lines first 
mentioned would be seen, as daring the American 
eclipse. 

What the polariscope has told us respecting the 
corona is in accordance with this view. 

In the same way the quality of the zodiacal light 
admits of being perfectly accounted for, without re- 
sorting to the hypothesis that this phenomenon is a 
terrestrial one.* 

The explanation thus put forward has at least the 
advantage of being founded on well-established rela- 
tions. We know that the auroral light is associated 
with the earth's magnetism, and that meteoric bodies 

* It was with some surprise that, at a late meeting of the Royal 
Astronomical Society, I heard Dr. Balfour Stewart put forward, even 
as a hypothesis, so startling a proposition as this. That the region of 
the counter-trades may be at times illuminated by electrical discharges 
will serve to account very well for the occasional phosphorescent appear- 
ance of the whole heavens at night — but the portion of the heavens 
illuminated by the zodiacal light has no relation whatever to the atmos- 
pheric region in which the counter-trades prevail. The hypothesia. 
indeed, in wholly untenable. 
5 



66 OTHER WORLDS THAN OURS. 

are continually falling upon the earth's atmosphere. 
We know, also, that the sun exerts magnetic influences 
a thousand-fold more intense than those of the earth, 
and that in his neighborhood there must be many 
million times more meteoric systems. 

But we have other and independent reasons, which 
must not be overlooked, for considering the corona to 
be of some such nature as I have suggested. Lever- 
rier has shown that there probably exists in the neigh- 
borhood of the sun a family of bodies whose united 
mass suffices appreciably to affect the motions of the 
planet Mercury. It would not be safe to neglect con- 
siderations thus vouched for. 

Mr. Baxendell, also, has shown that certain periodic 
variations in the earth's magnetism point to the ex- 
istence of such a family of bodies ; and he has been 
able to assign to them a position according well with 
that determined by Leverrier. 

Now, whatever opinion we form as to the exact 
character of the system of bodies pointed to by the 
researches of Leverrier and Baxendell — whether we 
suppose that system to form a zone around the sun,* 
or that (as I believe) the system is merely due to the 
aggregation of meteoric perihelia in the sun's neigh- 
borhood — we may be quite certain of this, that during 
a total solar eclipse the system could not fail to become 

* I am not here referring to Humboldt's notion that the zodiacal 
light is due to a zone of small bodies round the sun ; a view which only 
derives importance from the fact that Sir John Herschel has been at the 
pains to contradict it. It need hardly be said, that Sir John Herschel'a 
opinion has a weight which is altogether wanting to Humboldt's, so fa? 
as astronomical matters are concerned. 



WHAT WE LEARN FROM THE SUN. 67 

risible. Hence there is a double objection to the view 
put forward by Mr. Lockyer and others. In the first 
place, it fails to account for the appearance presented 
by the corona ; in the second place, it fails to render an 
account of the implied non-appearance of the system 
which, according to the researches of Leverrier and 
Baxendell, circles around the sun. 

It will be seen, in the chapter on " Meteors and 
Comets," how important a bearing these views respect- 
ing the nature of the corona have upon the history of 
the solar system. It has been partly for this reason 
that I have here briefly considered the matter; but 
fchere is another and a most important relation in which 
these views must be regarded. 

We know that the sun is the sole source whence 
light and heat are plentifully supplied to the worlds 
which circle around him. The question immediately 
suggests itself — Whence does the sun derive those 
amazing stores of force from whence he is continually 
supplying his dependent worlds ? We know that, were 
the sun a mass of burning matter, he would be con- 
sumed in a few thousand years. We know that, were 
he simply a heated body, radiating light and heat con- 
tinually into space, he would in like manner have 
exhausted all his energies in a few thousand years — a 
mere day in the history of his system. Whence, then, 
comes the enormous supply of force which he has 
afforded for millions on millions of years, and which 
also our reason tells us he will continue to afford while 
the worlds which circle around him have need of it — 
in other words, for countless ages yet to come ? 



68 OTHER WORLDS THAN OURS. 

Now, there are two ways in which the solar ener- 
gies might be maintained. The mere contraction of 
the solar substance, Helmholtz tells us, would suffice to 
supply such enormous quantities of heat, that if the 
heat actually given out by the sun were due to this 
cause alone, there would not, in many thousands of 
years, be any perceptible diminution of the sun's 
diameter. But, secondly, the continual downfall of 
meteors upon the sun would cause an emission of 
heat in quantities vast enough for the wants of all 
the worlds circling round him ; while his increase of 
mass from this cause would not be rendered perceptible 
in thousands of years, either by any change in his ap- 
parent size or by changes in the motions of his family 
of worlds.* 

It seems far from unlikely that both these process- 
es are in operation at the same time. Certainly the 
latter is, for we know, from the motions of the meteoric 
bodies which reach the earth, that myriads of these 
bodies must continually fall upon the sun. And if the 
corona and zodiacal light really be due to the existence 
of nights of meteoric systems circling around the sun, 
ot ,o the existence in his neighborhood of the peri- 
helia of many meteoric systems, then there must be a 



* Altogether undue stress has been laid upon the probable change iu 
the length of the year, owing to the downfall of meteors upon the sun'ii 
mass. It is forgotten that the crowded meteors forming the solar corona 
are already within the earth's orbit, and therefore already produce theii 
full effect on the length of the year. The subsidence of all these bodies 
at once upon the sun would not affect the length of the year, though il 
would lead to certain modifications in the secular perturbations of thf 
earth's orbit in figure and position. 



WHAT WE LEARN FROM THE SUN. 



6 9 



6upply of light and heat from this source, very nearly 
if not quite sufficient to account for the whole solar 
emission. 

It is well worthy of notice, too, that the association 
between meteors and comets has an important bear- 
ing on this question. We know that the most re- 
markable characteristic of comets is the enormous dif- 
fusion of their substance. Now, in this diffusion there 
resides an enormous fund of force. The contraction 
of a large comet to dimensions corresponding to a 
very moderate mean density would be accompanied 
by the emission of a vast supply of heat. And the 
question is worth inquiring into, whether we can in- 
deed assume that the meteors which reach our atmos- 
phere are solid bodies, and not rather of cometic dif- 
fusion ; since it is difficult otherwise to account for 
the light and heat which they emit. Friction through 
the rarer upper strata of our atmosphere will certainly 
not account for these phenomena ; nor, I think, will 
the compression of the atmosphere in front of the me- 
teors ; on the other hand,«*the sudden contraction of a 
diffused vapor would be accompanied by precisely 
such results. But, be this as it may, it is certain that 
a large portion of the substance of every comet is in a 
singularly diffused state. And since the meteoric sys- 
tems circling in countless millions round the sun are, 
in all probability, associated in the most intimate 
manner with comets, we may recognize in this diffu- 
sion, as well as in the mere downfall of meteors, the 
source of an enormous supply of light and heat. 

And lastly, turning from our sun to the other sun a 



7° 



OTHER WORLDS THAN OURS. 



which shine in uncounted myriads throughout space, 
we see the same processes at work upon them all. 
Each star-sun has its coronal and its zodiacal disks, 
formed by meteoric and cometic systems ; for other- 
wise each would quickly cease to be a sun. Each star- 
sun emits, no doubt, the same magnetic influences 
which give to the zodiacal light and to the solar co- 
rona their peculiar characteristics. And thus the 
worlds which circle round those orbs may resemble 
our own in all those relations which we refer to ter- 
restrial magnetism, as well as in the circumstance 
that on them also there must be, as on our own earth, 
a continual downfall of minute meteors. In those 
worlds, perchance, the magnetic compass directs the 
traveller over desert wastes or trackless oceans; in 
their skies, the aurora displays its brilliant streamers ; 
while, amid the constellations which deck their heav- 
ens, meteors sweep suddenly into view, and comets ex- 
tend their vast length athwart the celestial vault, a 
terror to millions, but a subject of study and research 
to the thoughtful. 



CHAPTER III. 



THE INFERIOR PLANETS. 



In considering the habitability of various portions 
of the solar system, we have to draw a marked distinc- 
tion between the planets which travel within the orbit 
of the earth and those which lie beyond its range. 
So far, indeed, as our belief in these orbs being in- 
habited is concerned, we may apply the same process- 
es of reasoning to one set of planets as to the other. 
Until it has been demonstrated that no form of life 
can exist upon a planet, the presumption must be that 
the planet is inhabited. But it is impossible to con- 
template the various members of our solar system, 
without being led to consider their physical habitudes 
rather with relation to the wants of such creatures as 
exist upon our own earth, than merely with reference 
to the existence of life of some sort upon their surface. 
Viewing Venus and Mercury in this way, we have a 
different set of relations to deal with than we find 
among the outer planets. We are struck, at once, with 
the marked effects which seem associable with their 
comparative proximity to the sun's orb. This feature 



72 



OTHER WORLDS THAN OURS. 



and the shortness of their period of revolution — that 
is, of their year — are the characteristic peculiarities 
we have to deal with. 

I would willingly pay some attention here to the 
story of Yulcan, the planet which has been supposed 
to circle yet more closely than Mercury around the 
centre of our system, were it not for the great doubt 
in which the existence of this planet seems'enshrouded. 
If, on the one hand, we have the evidence of Lescar- 
bault that, on a certain day, and at a certain hour, he 
saw a dark object, round like a planet, crossing the 
face of the sun, we have also the evidence of Liais, 
whose name is much better known among astrono- 
mers, that at that very hour there was no such object 
on the solar disk. There is nothing to render the ex- 
istence of an intra-Mercurial planet at all unlikely ; 
and there are many observations which scarcely seem 
explicable on any other hypothesis. Still, as yet we 
have not that clear and unmistakable evidence which 
would permit me to speak of Yulcan as a planet 
known to astronomers, and I wish, while within the 
bounds of the solar system, to limit 'myself to the con- 
sideration of bodies which have been recognized and 
examined. 

Mercury circles around the sun in the brief period 
of eighty-eight days, or rather less than three of our 
months. So that, if the planet has seasons, these must 
be severally about three weeks long. His distance 
from the sun varies between somewhat wide limits, 
owing to the eccentricity of his orbit. When he is 
nearest to the sun, he receives ten and a half times 



THE INFERIOR PLANETS. 73 

more liglit and heat from that luminary than we do ; 
but, when he removes to his greatest distance, the 
light and heat he receives are reduced by more than 
one-half. Even then, however, the sun blazes in the 
skies of Mercury with a disk four and a half times larger 
than that which he presents to the observer on earth. 

Undoubtedly these peculiarities, the shortness of 
the Mercurial year, and the immense amount of light 
and heat poured by the sun upon the planet, are cir- 
cumstances which do not encourage, at first sight, the 
belief that any creatures can subsist upon this planet, 
resembling those with which we are familiar. We see, 
at once, that all forms of vegetation in Mercury must 
differ in a very striking manner from those which exist 
upon the earth, because their structure has to be 
adapted to much more rapid changes of temperature. 
And the existence of a totally distinct flora suggests 
at once the belief that animal life on Mercury must be 
very different from what we see around us. 

Let us, however, proceed a few steps farther. 

It has been found that Mercury rotates upon his 
axis, and, if we may put faith in the observations of 
Schroter, the Mercurial day is only a few minutes 
longer than our own. But, though the fact of the 
planet's rotation has been observed, it has not been 
found possible to determine in what position the axis 
of rotation lies. It has been said that the planet's 
equator is much more inclined than the earth's to the 
plane in which the planet travels ; but little reliance 
can be placed on the evidence which has been adduced 
m favor of this view. 



74 



OTHER WORLDS THAN OURS. 



We are thus left altogether in doubt as to the na- 
ture of the Mercurial seasons. That the planet has 
seasons of some sort we are certain, because, even if 
the axis were so placed that perpetual spring reigned 
upon the planet — I mean, that the days and nights 
were at all times and in all places equal — yet his vary- 
ing distance from the sun would give changes of tem- 
perature quite as marked as those which characterize 
our seasons in England, and very much more marked 
than those known in tropical regions. Of course, if 
this is the actual arrangement, there are differeni cli- 
mates in different parts of the planet. Near his poles, 
the sun, though visible for half the Mercurial day, 
attains yet but a low elevation above the horizon ; just 
as he does on a spring day within our own polar cir- 
cles. At the equator the sun passes day after day to 
the zenith, and pours down upon the planet an amount 
of light and heat far exceeding the light and heat of 
our tropical climates. A sun immediately overhead, 
and showing a diameter varying from more than twice 
to more than three times that of our sun, must be a 
noble and maybe a terrible phenomenon in the skies 
of Mercury. 

There is yet another arrangement by which to a 
portion of the planet, at any rate, the Mercurial sea- 
sons might be tempered. If his axis is so placed that 
what would be the winter season, were his orbit not 
eccentric, takes place, for one hemisphere, when the 
planet is nearest to the sun, then undoubtedly it may 
very well happen (the inclination of his axis being suit- 
ably adjusted) that this so-called winter season is the 



THE INFERIOR PLANETS. 



75 



warmest part of the year for that hemisphere. In this 
case, there would be the least possible violence in the 
succession of the Mercurial seasons for that hemi- 
sphere. But in the other hemisphere the seasonal 
changes would be correspondingly intensified. 

In either of these cases, it is readily conceivable 
that even forms of life resembling those we are ac- 
quainted with on earth might exist on Mercury, and 
that without any special provision for tempering the 
great heat and light of the sun. Those regions which 
correspond to our temperate and tropical zones would 
indeed scarcely be habitable ; but the polar regions of 
the planet would not form a disagreeable abode. 

If, however, the equator of the planet is very much 
inclined to the plane in which Mercury travels, it can- 
not be doubted that no form of life known upon earth 
can possibly exist upon Mercury, without some special 
arrangements for tempering the seasonal changes. 
This will appear when we come to deal with the effect 
of the great inclination which some astronomers have 
ascribed to the equator of Yenus, and therefore we 
need not consider the relation with regard to Mercury, 
of whose axial inclination no trustworthy information 
has hitherto been obtained. 

It remains for us to consider what sort of provision 
may have been made to temper the great heat poured 
by the sun upon Mercury. 

The climate of a planet, considered generally, is 
largely influenced by the nature of the planet's atmos- 
phere. We have very clear evidence on this point, 
in the effects which we notice on our own earth. If 



j 6 OTHER WORLDS THAN OURS 

we ascend to the summit of a lofty mountain, we find 
the air mnch colder than at its base. In India, though 
the full heat of a tropical sun is poured day after day 
upon the snowy summits of the Himalayas, yet the 
air continues colder than in the bitterest midwinter 
weather experienced by us in England. Not that the 
solar rays have no power. The heat is, in reality, even 
greater than on the plains, because it has not been 
intercepted by vapor-laden air. But the air itself is 
not heated. Owing to its extreme rarity and dryness, 
it neither impedes the passage of the sun's heat to the 
earth, nor prevents the return of that heat from the 
earth by radiation or reflection ; and this very fact, 
that it does not impede the passage of heat, means 
nothing else than that the air does not become heated.* 
We have, then, so far as a rare atmosphere is con- 
cerned, two points to dwell upon — the readiness with 
which such an atmosphere permits the sun's heat to 
reach the surface of a planet, and the readiness with 
which it permits the planet's heat to pass away into 
space. Now, we might feel doubtful which of these 

* The following passage, quoted by Prof. Tyndall from Hooker's 
" Himalayan Journals," illustrates the peculiarities referred to above : 
"At 10,000 feet, in December, at 9 a. m., I saw the mercury mount to 
182°, while the temperature of shaded snow hardly was 22°. At 13,100 
feet, in January, at 9 a. m., it has stood at 98°, with a difference of 
68.2°, and at 10 a. m. at 114°, with a difference of 81.4°, while the 
radiating thermometer on the snow had fallen at sunrise to O.^ ." Such 
observations as these are well worth studying. It is interesting to con- 
sider that at the summit of the highest peaks of the Himalayas the mid- 
day heat of the sun must sometimes be near if not above the boiling 
point corresponding to those places, since water would boil on Mount 
Everest at a temperature of little more than 160°. 



THE INFERIOR PLANETS. 7? 

two effects was chiefly to be regarded, were it not that 
on our own earth we have experience of the effects of 
a very rare atmosphere. We know that the climate 
of very elevated regions is relatively much cooler than 
that of places on the plain. Thus we learn that the 
direct heating powers of the sun are not so much to 
be considered, in judging of the climate of any region, 
as the quality of the atmosphere. 

Yet we must not deceive ourselves by inferring 
that mere rarity of atmosphere can compensate fully 
for an increased intensity of solar heat. It is not true 
that the climate of a place on the slopes of the Andes 
or the Himalayas corresponds to that of a region on 
the plain which has an atmosphere equally warm. 
The circumstances are, in fact, wholly different. On 
the plain there is, it is true, the same amount of heat 
in the case supposed : but the air is denser and more 
moisture-laden; the nights are warmer because the 
skies are less clear and the heat escaping from the 
earth is intercepted by clouds or by the transparent 
aqueous vapor in the air ; and, lastly, there is not so 
great a contrast between the warmth of the air and 
the direct heat of the solar rays. 

If the atmosphere of Mercury, therefore, be exces- 
sively rare, as some have supposed, so as to afford an 
Alpine or Himalayan climate in comparison with the 
tremendous heat we should otherwise ascribe to the 
climate of the planet, there would by no means result 
a state of things resembling that with which we are 
familiar on earth. We must not, in our anxiety to 
people Mercury with creatures such as we know of, 



7 8 OTHER WORLDS THAN OURS. 

blind ourselves to the difficulties which have to be 
encountered. We cannot thin the Mercurial air, with- 
out adding to the direct effects of the sun upon the 
Mercurial inhabitants. Whether in this way we in- 
crease the habitability of the planet may be doubted 
when we consider that the direct action of the sun's 
rays upon the tropical regions of Mercury, thus de- 
prived of atmospheric protection, would produce a 
heat four or five times greater than that of boiling 
water. It will hardly be thought that the intense cold 
in the shade, or during the Mercurial night, would com- 
pensate for so terrible a heat. In fact, this view of 
the Mercurial climate would lead us to find a close 
resemblance between the inhabitants of the planet and 
the unfortunates described by Dante as doomed 

*" A sofferir torment! e caldi e gieli." 

It would seem hard to believe in the existence of any 
organized forms under such conditions, unless perhaps 
such " microscopic creatures, with siliceous coverings," 
as Whewell proposed to people Yenus with. 

However, we have yet to consider whether an 
atmosphere of a different sort might not be better 
suited to the requirements of Mercury. We have 
seen the effects of a rare atmosphere, let us inquire 
into those which might be ascribed to a dense one. 

The ordinary effect of a dense atmosphere we know 
to be an increase of heat, which is certainly not what 
we require in the case of Mercury. Nor are we fa- 
miliar with any region upon our earth in which a 
dense atmosphere produces a contrary climatic effect ; 



TEE INFERIOR PLANETS. 7g 

so tliat we have no analogy to support us in tlie belief 
that, possibly, a dense atmosphere might, under par- 
ticular circumstances, serve to guard a planet from the 
solar rays. It seems possible, however, that an atmos- 
phere might be so constituted as to remain almost con- 
stantly loaded with heavy cloud-masses. In this case, 
it by no means follows that such effects would follow 
as we ordinarily associate with a moisture-laden at- 
mosphere. Up to a certain point, doubtless, the in- 
crease of moisture in the air tends to an increase 
of warmth ; because the aqueous vapor exercises a 
greater effect in preventing the escape of heat from 
the earth than in guarding the earth from the solar 
rays. And, as I have said, the only climatic effect we 
can associate with the frequent presence of large 
quantities of aqueous vapor in the air, or therefore 
with an ordinarily clouded state of the sky, is that of 
a general increase of heat. But, just as we know that 
a cloudy day is not necessarily nor even commonly a 
warm day, it may well be that an atmosphere so dense 
as to be at all times cloud-laden serves as a protection 
from the sun's intense heat. So that, instead of assign- 
ing dense atmospheres exclusively to the more distant 
planets, as some astronomers have done, we might be 
led to see in an envelope of great density the means of 
defending the inhabitants of Mercury and Venus from 
the otherwise unedurable rays of their near neighbor 
the sun. 

Although Mercury is not a planet which can be satis- 
factorily examined with the telescope, yet, so far as can 
be judged from his aspect, his atmosphere is in reality 



go OTHER WORLDS THAN OURS. 

mucli denser than our earth's, and loaded with cloud- 
masses of enormous extent. Still the evidence on 
these points is far from satisfactory ; and there is one 
peculiarity of the planet which does not accord with 
this view of the constitution of his atmosphere. Un- 
doubtedly, if the light we receive from Mercury came 
from a cloudy envelope, it would be more brilliant than 
the light we should receive from the surface of con- 
tinents and oceans. In fact, the most brilliant light 
we could receive from a globe of a given size, placed at 
a given distance from the sun, would be that which 
would be reflected were such a globe covered with 
clouds. Now, there can be no doubt whatever that 
Mercury does not reflect the same proportion of light 
from his surface that some of the planets do. He 
would be, when favorably situated, the brightest of all 
the planets, were this so ; * though, seen as he always 
is, on the bright background of a full twilight sky, 
he would not make so striking an appearance as 

* Placing Mercury in perihelion and at his elongation, we get a half 
disk, the planet about 90,000,000 miles from us, and about 30,000,000 
from the sun, his diameter about 3,000 miles. Now, if we wish to com- 
pare the light he then sends us, with that of Jupiter at his brightest, on 
the assumption of equal reflective powers, we must take Jupiter at a 
distance of about 360,000,000 miles from us, and about 450,000,000 
miles from the sun, showing a full disk, his diameter about 90,000 miles 
(I put all the numbers round, for convenience of calculation). We find, 
then, that the ratio of Mercury's light to Jupiter's is 

1 (3,000) 2 m (9O,000) 2 

2 (9(y)00,000) 2 x (30,000,000) 2 S (360,000,000) 2 x (450,000,000)* 
or i (4) 2 (15) 2 : (30) 2 , or exactly 2 to 1. 

The observation above cited is sufficient to prove that a very different 
state of things actually prevails; in other words, that the reflective 
powers of the two planets are very different. Unless, indeed, Jupite: 
3hines in part by inherent light. 



THE INFERIOR PLANETS, %\ 

Jupiter does when in opposition. This, however, is 
not the case. I remember being mnch struck by the 
superior light of Jupiter, on the afternoon of February 
23, 1868, when the two planets were very close to- 
gether, Mercury being nearly at his brightest, whereas 
Jupiter, then near conjunction, was considerably less 
bright than when in opposition. Yenus was close by, 
and outshone both Mercury and Jupiter. 

It seems difficult, therefore, to believe that the 
light of Mercury comes from a cloudy envelope. But 
there is still one supposition which may restore our be- 
lief in the habitability of the planet by creatures not 
very different from those which inhabit our earth. If 
it has a double cloud-envelope, the upper like our cir- 
rus clouds, less compact than the lower, and permit- 
ting a portion of the sunlight to pass through, it is 
possible that the lower cloud-layer would be seen 
partly in shadow. I must admit that the explanation 
is not quite satisfactory, because, just as much light as 
the outer clouds intercepted they would reflect ; still, 
it is conceivable that the usual arrangement of these 
clouds may be such, that to us, who do not look at the 
planet in the direction in which the sun's rays fall, 
but somewhat aslant, the shadows of the upper clouds 
upon the dense and compact lower envelope may be 
rendered in large part visible. 

After all, the reader may prefer the view which 
recognizes in the polar regions of Mercury places 
suitable for organic existences, while the equatorial 
and neighboring regions are zones of lire, whose dan- 
gers the bravest Mercurials, the very Livingstones 
6 



g 2 OTHER WORLDS THAN OURS. 

upon that planet, would not dare to face. We may 
picture to ourselves, on this view, the various con- 
trivances by which the inhabitants of the two polar 
(that is, in reality, temperate) circles manage to com- 
municate. There may be regions where favoring cir- 
cumstances narrow the uninhabitable zone so much 
that the inhabitants of one polar circle may travel to 
the other (or, at least, cross the most dangerous por- 
tion of the hot zone) in the course of the Mercurial 
night. Or perhaps tunnels may be run, or sheltered 
cuttings made, along which the voyage may be made 
in comparative safety. Ocean communication there 
can be none, if the Mercurial sides are clear, since the 
sun's heat on the tropical zone would suffice to boil 
away any water which might find its way there. 

Certainly, the smallness of the planet and the di- 
minished effects of gravity upon its surface would 
tend to make communication much easier, and the 
construction of protective tunnels or cuttings a com- 
paratively light task. What the exact force of grav- 
ity at the surface of Mercury may be we do not know, 
because our means of determining the mass of the 
planet are not so satisfactory as in the case of the 
other primary members of the solar system. If Mer- 
cury had a satellite, we could tell bis weight at once. 
If he were as large as Yenus, we could tell his weight 
by observing his effect in disturbing the motions of 
that planet. As it is, the only means we have of 
weighing Mercury is the observation of his effect in 
disturbing any comet which may pass near him. In 
this way the planet has been weighed, but the balance 



THE INFERIOR PLANETS. 



83 



thus employed is not a satisfactory one altogether, be- 
cause we are not quite certain how much of the dis- 
turbance of a comet when near Mercury is due to the 
planet's attraction. Formerly, it was supposed that 
the mean density of Mercury was equal to that of 
lead; but, from the perturbations of Encke's comet in 
Mercury's neighborhood, astronomers have been led to 
the conclusion that the density of the planet is not more 
than one-sixth greater than our earth's. It follows 
that, as his diameter is little more than three thousand 
miles, our earth is about fifteen times as heavy as 
Mercury. Gravity at his surface is such, that a pound 
weight of ours would weigh rather less than seven 
ounces on Mercury. Hence the creatures which seem 
to us most unwieldy — the elephant, the hippopotamus, 
and the rhinoceros, or even those vast monsters, the 
mammoth, the mastodon, and the megatherium, 
which bore sway over our globe in far-off eras — might 
emulate on Mercury the agility of the antelope or the 
greyhound. 

There can be no doubt that, where gravity acts so 
feebly, all engineering operations would be rendered 
very much simpler — bridges could have a wider span, 
and yet be stronger than our terrestrial ones, buildings 
could be loftier and yet be raised more easily, and 
transit of all sorts would be effected much more readily, 
while at the same time the distances to be traversed are 
very much less than on our earth, since the surface of 
Mercury is little more than one-seventh of the earth's. 

The peculiarities which characterize Yenus are for 
the most part similar in kind to those we have had 



a 4 OTHER WORLDS THAN OURS. 

to consider in the case of Mercury. But at the outset 
of our inquiries into the physical habitudes of this 
most beautiful planet, we must point to the striking 
resemblance which it bears, in some respects, to our 
own earth. So far, indeed, as telescopic and physical 
researches have yet led us, the planet Mars, as we 
shall presently see, appears to exhibit habitudes more 
closely corresponding to those we are apt to consider 
essential to the wants of living creatures. But in size, 
in situation, and in density, in the length of her sea- 
sons and of her rotation, in the figure of her orbit and 
in the amount of light and heat she receives from the 
sun, Venus bears a more striking resemblance to the 
earth than any orb within the solar system. In fact, 
there is no other pair of planets between which so 
many analogies can be traced as between Venus and 
the earth. Uranus and Neptune are similar in many 
respects, but they differ in at least as many. Jupiter 
and Saturn are, in a sense, the brother giants of the 
solar scheme, while the dwarf orbs Mars and Mercury 
present many striking points of similarity; but be- 
tween neither of these pairs can we trace so many fea- 
tures of resemblance as those which characterize the 
twin planets Venus and Terra, while the features of 
dissimilarity in either pair are perhaps even more ob- 
vious than the points of resemblance. Had Venus 
but a moon as the earth has, we might doubt whether, 
in the whole universe, two orbs exist which are so 
strikingly similar to each other. 

And here we may pause for a moment to consider 
one of the most perplexing enigmas that has ever been 



THE INFERIOR PLANETS. 85 

presented to astronomers. Are we indeed certain that 
Venus lias no moon ? The question seems a strange 
one, when it is remembered that year after year 
Venus has been examined by the most eminent mod- 
ern observers, armed with telescopes of the most ex- 
quisite defining power, without any trace of a com- 
panion orb' being noticed. Nor, indeed, can any 
reasonable doubts be entertained respecting the moon- 
less condition of Venus, by those who appreciate the 
character of modern telescopic observations ; and yet, 
if I had begun this paragraph by stating the evidence 
in favor of the existence of a satellite, I believe that 
nearly every reader would have come to the conclu- 
sion that most certainly the Planet of Love has an 
attendant orb. They are not amateur observers only, 
who have seen a moon attending on Venus, but such 
astronomers as Cassini and Short, the latter with two 
different telescopes and four different eye-pieces. 
Four times, between May 3 and 11, 1761, Montaigne 
6aw a body near Venus, which presented a phase 
similar to that of the planet, precisely as a satellite 
would have done. From these observations M. Bau- 
douin deduced for the new star a diameter of about 
two thousand miles, and a distance from Venus nearly 
equal to that which separates the moon from the 
earth. In March, 1761, again, Hodkier saw the enig- 
matical companion ; Horrebow saw it a few days 
later ; and Montbaron saw it in varying positions on 
March 15, 28, and 29. Lastly, Scheuten, who wit- 
nessed the transit of Venus in 1761, declares that he 
saw a satellite accompany Venus across the face of 



56 OTHER WORLDS THAN OURS. 

the sun. So that we cannot be greatly surprised that 
even so skilful an observer as the late Admiral Smyth 
was disposed to believe in the existence of a satellite 
of Yenus. " The contested satellite is, perhaps," he 
remarked, " extremely minute, while some parts of its 
body may be less capable of reflecting light than 
others ; and when the splendor of its primary and our 
inconvenient station for watching it are considered, it 
must be conceded that, however slight the hope may 
be, the search ought not to be relinquished." 

There is little occasion to dwell upon Yenus's 
moonless condition, because the inferior planets are 
much less affected by the want of a moon than a supe- 
rior planet would be. The service rendered by our 
own moon, as a luminary of the night, is the least 
important work she does in our behalf. It is as the 
chief regulator of the tides that the moon befriends 
us most usefully. JSTow, Yenus has no need of lunar 
tides. Assuming that she has oceans such as those 
which exist upon the earth, her solar tides must be 
about two and a half times as high as the solar tides 
raised in our own oceans. And since our lunar tidal 
wave is about two and a half times as high as the 
solar one, we have tides ranging between the highest 
spring tides, which are three and a half times as high 
as the solar tide alone, and the lowest neap tides, 
which are only one and a half times as high as the 
solar wave. Yenus has constant tides, therefore, cor- 
responding very closely to the mean tides on our own 
earth ; and therefore perfectly well adapted to sub- 
serve all the purposes winch our tides render us, only 



THE INFERIOR PLANETS. $ ? 

with, less variety in their mode of operation. Mer- 
cury also has sufficiently high solar tides, supposing he 
has extensive oceans (which may reasonably be ques- 
tioned), since the smallness of his dimensions, tending 
of course to diminish the difference of action on which 
the sun's tidal influence depends, is fully compensated 
by his great proximity to that orb. 

Yen us has a year of two hundred and twenty-four 
days, seventeen hours, very nearly, and her distance 
from the sun, which varies little during the course of 
a year, is somewhat less than three-fourths of that 
which separates the sun from us. Her day is about 
thirty-five minutes shorter than ours, and her globe 
somewhat smaller than the earth's. 

It is clear that, merely in the greater proximity 
of Venus to the sun, there is little to render at least 
the larger proportion of her surface uninhabitable by 
such beings as exist upon our earth. The sun, as seen 
in her skies, has a diameter one-third larger than he 
presents to us ; and his apparent surface-dimensions, 
on which, of course, his heating and illuminating 
powers depend, are greater in the proportion of about 
sixteen to nine. This undoubtedly would render his 
heat almost unbearable in the equatorial regions of 
Yenus, but in her temperate and sub-arctic regions a 
climate which we should find well suited to our re- 
quirements might very well exist ; while her polar 
regions might correspond to our temperate zones, and 
be the abode of the most active and enterprising races 
existing upon her surface. 

Here, however, we have been supposing that 



38 OTHER WORLDS THAN OURS. 

Venus has seasons resembling our own in character, 
— in other words, that her axis of rotation is inclined 
at about the same angle to the plane in which she 
travels. Observations have been made, according to 
which a very different state of things would appear to 
prevail. It has been said, on the authority of ob- 
servers of some eminence, that her axis is inclined 
only 15° to the plane of her orbit.* If this is really 
the case, a number of singular and somewhat compli- 
cated relations are presented, the result of which it 
may be interesting to exhibit to the reader — espe- 
cially as there is very little doubt that in the case of 
Uranus an axial peculiarity of this sort actually exists.f 

In the first place, the arctic regions of Yenus ex- 
tend within fifteen degrees of her equator (if the axis 
is really bowed as supposed), while the tropics ex- 
tend within fifteen degrees of her poles — so that two 
zones, larger by far than the temperate zones of 
our earth, belong both to her arctic and to her 
tropical regions. It is difficult to say whether her 
equatorial, her polar, or her arctico-tropical regions 
would be, to our ideas, the least pleasing portion of 
her globe. 

An inhabitant of the regions near either pole has to 

* Why is it that, in so many works of popular astronomy, the mis- 
take is made of giving the inclination of a planet's equator to the orbit 
as the inclination of the axis to that plane ? In nine out of ten astro- 
comical works, the inclination of the earth's axis to her orbit is given 
as 23^° ; were this the case, the larger part of the earth would be unin- 
habitable. 

f If the observations of De Vico may be trusted, the inclination of 
Venus, though less than *75°, is still so considerable (about 55°) as to 
justify the general conclusions deduced in the following paragraphs. 



THE INFERIOR PLANETS. 89 

endure extremes of heat and cold, such as would suffice 
to destroy nearly every race of living beings subsisting 
upon the earth. During the summer, the sun circlea 
continually close to the point overhead, so that, day 
after day, he pours doT\n his rays with an intensity of 
heat and of light exceeding nearly twofold the midday 
light and heat of our own tropical sun. Only for a 
short time, in autumn and in spring, does the sun rise 
and set in these regions. A spring or autumn day, 
like one of our days at those seasons, lasts about twelve 
hours ; but the sun attains at noon, in spring or autumn, 
a height of only a few degrees above the horizon. 
Then presently comes on the terrible winter, lasting 
about three of our months, but far more striking in its 
characteristics even than the long winter nis;ht of our 
polar regions. For, near our poles, the sun approaches 
the horizon at the hour corresponding to noon ; and 
though he does not show his face, he yet lights up the 
southern skies with a cheering twilight glow. But 
during the greater part of the long night of Venus's 
polar regions, the sun does not approach within many 
degrees of the horizon. Nay, he is farther below the 
horizon than the midnight sun of our arctic regions. 
Thus, unless the skies are lit up with auroral splen- 
dors, an intense darkness prevails during the polar 
winter, which must add largely to the horrors of that 
terrible season. Certainly, none of the human races 
upon our earth could bear the alternations between 
these more than polar terrors and an intensity of 
summer heat far exceeding any with which we are 
familiar on earth. 



9° 



OTHER WORLDS THAN OURS. 



Let us see whether the equatorial regions are more 
pleasing abodes. 

In these parts of Venus there are two summers, 
corresponding to the spring and autumn of the polar 
regions. At these seasons, the sun rises day after day 
to the point overhead, and the weather corresponds for 
a while to that which prevails in the tropical regions of 
our own earth. But between these seasons the sun 
passes away alternately to the northern and southern 
skies. During the season corresponding to summer, 
he is above the horizon nearly throughout the twenty- 
three and a third hours of Venus's day ; * but he at- 
tains no great elevation, travelling always in a small 
circle close around the northern pole. During the 
season corresponding to winter, he is above the horizon 
only a very short time each day,f and is always close 

* On the equator itself, as on our own, the day is always equal in 
length to the night. The above account corresponds to a place near the 
borders of the equatorial zone. 

f In Admiral Smyth's " Celestial Cycle," the only work in which, so 
far as I am aware, the effects of the inclination ascribed to Venus's axis 
have been at all considered, it is stated that in the year of Venus there 
are but nine and a quarter of her days, " reckoned by the sun's rising 
and setting, owing to which the sun must appear to pass through a 
whole sign in little more than three-quarters of her natural day." He 
does not give any reasons for this remarkable statement, which most 
certainly is not correct. In all places outside the arctic circles of Venus, 
the year contains as many natural days as there have been rotations of 
Venus, wanting one only (as in the case of our own earth) ; in the re- 
maining regions there will be more or fewer days, according as the 
station considered is nearer to or farther from the arctic circle. Smyth'a 
remark that the varying amplitude of the sun (his distance, that is, from 
the east and west points), at rising or setting, would give travellers on 
Venus readier means than our seamen have, of determining the longi- 
tude, is just. But the problems involved must be very difficult, and I 



THE INFERIOR PLANETS. gl 

to the south, attaining only an elevation of a few de- 
grees at noon. Thus we have the following curious 
succession of seasons : At the vernal equinox a summer 
much warmer than our tropical summers ; about fifty- 
six clays later, or at the summer solstice, weather resem- 
bling somewhat the spring of our temperate zones, only 
that the night is exceedingly short ; yet fifty-six days 
later there is another summer, as terrible as the for- 
mer ; and lastly, at the winter solstice, the days are 
shorter and the cold probably more intense than in the 
winter of places near our arctic circles. In such regions 
the contrasts, rather than either of the extremes of 
climate, would be most trying to terrestrial races ; and 
it is scarcely too much to say that no races subsisting 
upon our earth could possibly endure such remarkable 
changes, succeeding each other so rapidly. 

Lastly, the beings who inhabit the wide zones 
which are at once tropical and arctic have climates 
ranging between the two limits just considered. If 
they are near the equatorial regions, they suffer from 
all the vicissitudes of the equatorial climate, with this 
further tribulation, that, in midwinter, they do not see 
the sun even at midday, a circumstance by no means 
compensated (according to our ideas) by the fact that 
near the summer solstice the sun does not set. If they 
are near the polar regions, they have a summer even 
more terrible than the polar summer, and a winter 
scarcely less dreary and bitter. 

wish her mathematicians joy of them. The cadets in our schools and 
training-ships have an easy time of it, compared with the unfortunate 
beings who are to officer the ships of Yenus — always supposing her axif 
is inclined as we have been assuming. 



2 2 OTHER WORLDS THAN OURS. 

Fortunately for our belief in the habitabiiity of 
Venus, astronomers are far from accepting with con- 
fidence the assertions of those observers who have as- 
signed to Venus an inclination so remarkable. If her 
inclination should at all resemble the earth's, there is 
every reason to believe that her physical habitudes 
also resemble those of the earth. In this case, the 
argument from analogy, presented in the opening 
chapter of this work, seems to force upon us the con- 
clusion that she is inhabited ; while we may believe, 
though perhaps with less confidence, that a close re- 
semblance subsists between the creatures which people 
her surface and those with which we are acquainted. 

We have no direct evidence, indeed, on which to 
ground our belief that the greater proximity of Venus 
to the sun may not be accompanied by any very re- 
markable peculiarities in the characteristics of her cli- 
mate. But we have an indirect argument of some 
strength. If Venus is much nearer than the earth to 
the sun, the earth, in turn, is much nearer to the sun 
than Mars is. Yet, as we shall see in the next chap- 
ter, we have clear evidence from telescopic observa- 
tion, and still clearer evidence as the results of spec- 
troscopic research, that the climatic arrangements on 
Mars do not differ in any remarkable degree from 
those of our own earth. It would follow, therefore, as 
at least probable, that a similar resemblance prevails 
between the climate of the earth and that of Venus. 
So that, despite the claim which Dr. Whewell has put 
in for microscopic animalcules with siliceous coverings 
as the sole inhabitants of Venus, I can find no reason 



THE INFERIOR PLANETS. 93 

(if the abnormal axial inclination above considered is 
once disproved) for denying that she may be the abode 
of creatnres as far advanced in the scale of creation as 
any which exist upon the earth. 

Gravity at the surface of Yenus is so nearly equal 
to terrestrial gravity, that the difference is altogether 
insufficient to introduce any noteworthy effects. The 
delicate adjustment of the sap-passages of plants to the 
force of terrestrial gravity, which Dr. Whewell notices 
in his ' Bridge water Treatise,' might indeed be dis- 
turbed, if the earth's gravity were suddenly made 
equal to that of Yenus. But it would be strangely to 
limit our conception of Nature's powers of adaptation, 
to suppose that therefore there can be no vegetation 
on Yenus resembling that with which we are familiar. 

Yenus is the only planet the extent of whose at- 
mosphere has been carefully estimated. If Yenus had 
no atmosphere, she would present, when horned, a semi- 
circular convexity ; whereas the refractive effects of an 
atmosphere, by causing the sun to illumine rather 
more than a full hemisphere, would tend to lengthen 
her horns. It has been found that her convexity when 
she is horned exceeds a semicircle, and, from the ob- 
served extent of this excess, it has been calculated 
that her atmosphere is so far more extensive than ours 
as to make its refractive effects on a body near the 
horizon about one-third greater. So that, as this is 
about the proportion in which the diameter of the siin 
as seen from Yenus exceeds that which he presents to 
us, the inhabitant of Yenus, like the inhabitant of our 
earth, sees the sun fully raised above the horizon at 



94 



OTHER WORLDS THAN OURS. 



the moment when, but for refraction, his orb would be 
just concealed beneath it. 

Of the constitution of the atmosphere of Yenus we 
know little. The spectrum of her light shows the dark 
lines which belong to the solar spectrum, and the 
Padre Secchi has noticed certain faint lines, which 
seem to indicate the presence of aqueous vapor in the 
atmosphere of the planet. But he scarcely gives sat- 
isfactory evidence that the lines he has thus seen were 
not due to the absorption exercised by aqueous vapor 
in our own atmosphere. The same observer finds, in 
the strengthening of the nitrogen lines near the F line 
of the spectrum, evidence that the atmosphere of Ye- 
nus is constituted very similarly to the air we breathe. 

On the whole, the evidence we have points very 
strongly to Yenus as the abode of living creatures not 
unlike the inhabitants of earth. With the sole excep- 
tion of the inclination, which has been, without suffi- 
cient evidence, assigned to the planet's equator, I can 
see nothing which can reasonably be held to point to 
an opposite conclusion. Certainly the strong light 
which the sun pours upon Yenus need least of all be 
objected to, since, if there is one adaptati ve power which 
Nature exhibits more clearly than another, it is that 
by which the various creatures we are acquainted with 
are enabled to live in comfort under all degrees of 
light, from the obscurity in which the mole pursues his 
subterranean researches, to the blazing light of the 
noonday sun toward which (in fable, if not in fact) the 
eagle turns his unshrinking eyes. 

There is one peculiarity which yet remains to be 



THE INFERIOR PLANETS. g$ 

noticed. Many are disposed to find, in the beauty of 
the celestial objects which deck the skies of different 
planets, a certain proof that reasoning beings must 
exist who can appreciate the display. Surely the 
argument has very little force, since we know that 
myriads on myriads of ages must have passed, during 
which the glories of our own heavens were displayed, 
night after night, with none to regard them. The 
moon has passed through all her phases, the star of 
morning and of eve has shed its soft radiance upon the 
terrestrial landscape, Jupiter and Saturn have pursued 
their stately courses among the fixed stars, and the 
glories of those constellations which shine with equal 
splendor upon all the planets of the solar scheme 
have been displayed in all their unchanging magnifi- 
cence, while as yet our earth was the abode hut oi 
hideous reptiles, or of yet more monstrous creatures in 
forest and in plain. 

If this argument were really of force, doubtless 
there are no planets in the whole range of the solar 
system to which it might not be applied. Each has 
some special object of beauty in its heavens, which is 
not exhibited to the rest. Certainly Mercury and 
Yen us are no exceptions to this rule. The inhabitant 
of Mercury sees in Venus an orb which, when favor- 
ably situated, far outshines in splendor the brightest 
of the planetary orbs seen in our skies. So far, indeed, 
as light-giving power is concerned, Yenus must be no 
contemptible moon to the Mercurials when she is nearly 
in opposition. Our earth, too, with its companion 
moon, must form a noble object in the sky of Mercury, 



9 & OTHER WORLDS THAN OURS. 

though, without telescopic aid, the moon perhaps may 
not be separately visible. To the inhabitants of Yenus, 
Mercury and the earth must be splendid objects. The 
former would not only appear much larger than to 
ourselves, but, being seen almost as favorably as we 
see Yenus, would form a much more striking object in 
the morning or evening sky of that planet. The earth, 
as seen by the inhabitants of Yenus, must shine much 
more splendidly than Jupiter does in our skies. Our 
moon must be distinctly visible, so that, without the 
aid of any telescope, the inhabitant of Yenus has such 
evidence of the Copernican theory as would suffice, if 
properly handled, to rout the ranks of the Ptolemaists, 
supposing there have ever been people in Yenus foolish 
enough to imagine the tiny globe they live upon to be 
the centre of the universe. 



CHAPTEE IT. 

MAES, THE MINIATURE OF OUR EARTH. 

It is singular that, among all the orbs which circle 
around the sun, one only, and that almost the least of 
the primary planets, should exhibit clearly and unmis- 
takably the signs which mark a planet as the abode 
of life. We have examined Mercury and Venus, the 
only other orbs which belong, like the earth and Mars, 
to the scheme of the minor planets, and we have found 
little to guide us to any certain conclusion respecting 
their physical habitudes. When we pass beyond the 
wide gap which separates the minor planets from the 
giant members of the solar family, we shall find much 
to attract our admiration, much to force upon us the 
belief that these orbs have been created to be the 
abodes of even nobler races than those which subsist 
upon our earth ; but Ave shall find little to justify us 
in asserting that they resemble the earth in those habi- 
tudes which seem essential to the wants of terrestrial 
races. The planet Mars, on the other hand, exhibits 
in the clearest manner the traces of adaptation to the 
wants of living beings such as we are acquainted with, 

Processes are at Work out yonder in space which ap 

7 



98 OTHER WORLDS THAN OURS. 

pear utterly useless, a real waste of Nature's energies, 
unless, like their correlatives on earth, they subserve 
the wants of organized beings. 

I would not indeed insist, as some have done, too 
strongly upon this argument. I know that on every 
side we see tokens of an exuberant activity in Nature* 
which, according to our ideas, may appear to savor of 
wastefulness. The cloud which has been raised by 
the solar energies from tropical seas, and which the 
winds have wafted over continents, may shed its waters 
on the sea or in the desert, where seemingly they are 
wholly wasted. Winds may spend their force appar- 
ently in vain. And in a thousand ways Nature's busy 
forces may be at work where we, in our short-sighted- 
ness, can see no useful purpose which they subserve. 

But there is a marked distinction between such 
apparent instances of wasteful action, and the system- 
atic processes which are taking place over the globe of 
Mars. 

Little as we can appreciate the real character of 
Nature's work upon our earth, we can yet dimly trace 
out a necessity (depending upon the order which actu- 
ally exists) for that which yet appears to resemble 
waste. We see, for instance, that if a country or a 
continent is to be provided with a due supply of rain, 
without supernatural intervention at every step of the 
process, that result can only be secured by what may 
be described as a random distribution, involving always 
what to us resembles waste. If, out of a thousand 
showers, ten only fall so as to be useful to the land, 
the object of Nature is subserved, and the useful rain 



MARS, THE MINIATURE OF OUR EARTH. 99 

falls serve to explain the seemingly wasted ones. In 
reality, of course, there has not been a random distri- 
bution, nor has there been any waste ; I infer, merely, 
that a sort of purpose is, in such a case, dimly seen, 
even by man, who can see so short a distance into the 
workings of the Almighty. 

But in the case of Mars we have no such explana- 
tion of the processes we observe, if we dismiss our be- 
lief that he is the abode of living creatures. For if 
Mars be, indeed, untenanted by any forms of life, then 
these processes going on year after year, and century 
after century, represent an exertion of Nature's ener- 
gies which appears absolutely without conceivable 
utility. If one cloud, out of a hundred of those which 
shed their waters upon Mars, supplies in any degree 
the wants of living creatures, then the purport of those 
clouds is not unintelligible ; but if not a single race of 
beings peoples that distant world, then indeed we seem 
compelled to say that, in Mars at least, Nature's forces 
are wholly wasted. Such a conclusion, however, the 
true philosopher would not care needlessly to adopt. 

Let us consider what astronomy has taught us re- 
specting the ruddy planet. 

The globe of Mars is about five thousand miles in 
diameter, so that his linear dimensions bear to those of 
the earth the proportion of about five to eight. His 
surface, therefore, is less than that of the earth in the 
proportion of about twenty-five to sixty-four, or, more 
exactly (and more conveniently), the surface of the 
earth is two and a half times as extensive as that of 
Mars. 



iOO OTHER WORLDS THAN OURS. 

The substance of Mars has an average density 
rather less than three-fourths of our earth's, or very 
nearly four times that of water. Thus gravity at his 
surface is much less than terrestrial gravity. It is, in 
fact, even less than gravity at the surface of Mercury, 
insomuch that one of our pound weights placed at the 
surface of Mars would weigh but 6 ozs. 3 dwts., in- 
stead of nearly seven ounces as on Mercury. I have 
already dwelt on the effects of such a relation as this, 
and shall have occasion, when describing the habi- 
tudes of Jupiter, to discuss the converse relation. But 
I may remark, in passing, how singular it is that we 
should be compelled to people the smallest planets 
with the largest inhabitants, if we wish to bring the 
inhabitants of different orbs to about the same scale 
of activity. A Daniel Lambert on Mars would be 
able to leap easily to a height of five or six feet, and 
he could run faster than the best of our terrestrial 
athletes. A man of his weight, but proportioned 
more suitably for athletic exercises, could leap over a 
twelve-feet wall. On the other hand, a light and ac- 
tive stripling removed to Jupiter would be scarcely 
able to move from place to place. On the sun his 
own weight would simply crush him to death. 

Mars travels in an orbit of considerable eccen- 
tricity ; in fact, the centre of his orbit is no less than 
thirteen millions of miles from the sun. Accordingly, 
the light and heat he receives from that luminary 
vary to an important extent. In fact, he gets about 
half as much heat and light again when in perihelion 
as when in aphelion. This circumstance affects to an 



MARS, THE MINIATURE OF OUR EARTH. 101 

important extent the climatic relations of his two 
hemispheres, as we shall presently see. 

When Mars is at his mean distance from the sun, 
the light and heat he receives are less than ours in the 
proportion of about four to nine. The length of his 
year also constitutes a noteworthy circumstance in 
which his habitudes differ from those of our earth. 
His year contains very nearly six hundred and eighty 
seven of our days, so that each of the Martial quarters 
lasts about five and two-thirds of our months. But, 
owing to the eccentricity of his orbit, the winter and 
summer of the northern and southern hemispheres are 
not equal. The Martial day is nearly forty minutes 
longer than ours.* 

His equator is inclined at an angle of about twen- 
ty-seven and a quarter degrees to the plane of his 
orbit, and as the corresponding inclination in the case 
of the earth is about twenty- three and a half de- 
grees, it will be seen that his seasonal changes do not 
differ much in character, so far at least as they depend 
on inclination, from our own. 

The axis of Mars is so situated that the summer 
of his northern hemisphere occurs when he is at his 
greatest distance from the sun. The same relation 
holds in the case of the earth, the sun being one mill- 
ion five hundred thousand miles nearer to us in win- 
ter than in summer, whereas, to those who live in the 

* More exactly, the length of the Martial day is 24h. 37m. 22.735s, 
This estimate I have obtained by comparing pictures taken by Hooke in 
1666, and by Dawes and Browning in 1866-1869 — with precautions 
sufficing to secure that no complete rotation should anywhere be lost 
sight of. 



102 OTHER WORLDS THAN OURS. 

southern hemisphere, he approaches nearer in summer 
than in winter. But the effects resulting from the 
relation in the case of Mars must be very much more 
striking than those we recognize. For, whereas the 
sun gives only one-fifteenth more heat to the whole 
earth in January than he does in July, the sun of 
Mars gives half as much light again in perihelion as 
in aphelion. The summer of the northern hemisphere 
of Mars must be rendered much cooler and the winter 
much warmer by this arrangement. On the other 
hand, the contrast between the summer and winter of 
the southern hemisphere is rendered more striking 
than it otherwise would be. 

It is, however, the telescopic aspect of Mars, rather 
than relations such as we have been dealing with, 
that affords the most interesting evidence respecting 
the fitness of the planet to be the abode of living crea- 
tures. Although the least but one among the prima- 
ry planets — a mere speck compared with Jupiter and 
Saturn — Mars has been examined more minutely and 
under more favorable circumstances than any object 
in the heavens except the moon. He does not ap- 
proach us so closely as Yenus, nor does his disk ap- 
pear so large as Jupiter's, yet he is seen more favor- 
ably than the former planet, and on a larger scale, in 
reality, than the latter. In fact, whereas Yenus is 
one of the most unsatisfactory of all telescopic objects, 
Mars is one of the most pleasing ; and, whereas Jupi- 
ter is always more than three hundred and eighty 
millions of miles from us, Mars sometimes approaches 
us within less than forty millions of miles. 



MARS, THE MINIATURE OF OUR EARTH. 1G j 

Yet even this distance is enormous, and it affords 
high evidence of the skill with which modern tele- 
scopes are constructed and used, that astronomers 
should have been able to span that mightv gulf, and to 
bring from beyond it reliable information respecting 
the structure of so distant a world. 

Such information has been brought, however, and 
is full of interest. 

Yiewed with the naked eye, the most remarkable 
feature Mars presents is his ruddy color. In the tele- 
scope this color is not lost, but, instead of characteriz- 
ing the whole surface of the planet, it is confined to 
particular regions — the intermediate parts being for 
the most part darker, and of a somewhat greenish hue. 
But a noteworthy feature adds largely to the beauty 
of the picture presented by the globe of Mars. Two 
bright spots of white light are seen on opposite sides 
of his disk, presenting precisely such an appearance 
as we might imagine the snowy poles of our earth to 
exhibit to an astronomer on the planet Yenus. 

Toward the edge of the disk, the ruddy and the 
greenish tracts are lost in a misty whiteness, which 
grows gradually brighter up to the very border of the 
planet. We shall presently see that this peculiarity, 
rightly understood, is one of the most instructive fea- 
tures of the planet's aspect. 

Xo telescopist has yet been able to recognize a 
satellite attending on the Planet of War. 

It was discerned, more than two hundred years ago, 
that the reddish spots on Mars, and the darker regions 
which lie between them, are not accidental or variable 



104 OTHER WORLDS THAN OURS. 

phenomena, but represent permanent peculiarities of 
the Martial surface. Cassini, with one of those outra- 
geously long telescopes which were used before the 
invention of achromatic refractors, was the first to dis- 
cover this. But the ingenious Hooke seems to have 
obtained better views of Mars in 1666. At least, his 
pictures of the planet are the only ones taken in the 
seventeenth century, in which I can recognize the 
now well-known aspect of the Martial continents and 
oceans. 

Since then, Maraldi and the Herschels, Arago, 
Secchi, Kunowski, Beer, and Madler, and a host of 
other eminent astronomers, have not thought the study 
of the planet's aspect beneath their notice. Within 
the last few years, also, this work has been prosecuted 
by Nasmyth and Jacob, Delarue and Phillips, and 
finally and most successfully by Lockyer and Dawes. 
The last-named observer, especially, whose acuteness 
of vision earned for him the title of the eagle-eyed, 
took so many and such admirable views of the planet 
as to render it possible to form a globe of Mars. Sir 
William Herschel had charted the planet, and Messrs. 
Beer and Madler had made improved Martial maps ; 
while Prof. Phillips, from observations made by him- 
self and Mr. Lockyer, had constructed two globes of 
Mars in which many features were presented. But 
Mr. Dawes's pictures of the planet were sufficient, when 
carefully compared, for the formation of a globe in 
which no large area of the planet should be left bare of 
details. He intrusted to me no less than twenty-seven 
drawings of Mars, the choicest specimens of a very 



865 Jan.l 7 h 45 m 



I864jNov.20 ll h 36 n 



1864 Nov 10 12 K 6 TO 



1864 Nov 23 I2 h 24 r 



Creenwich Me an Time 



THE PLANET MARS 

( Dawes.) 



MARS, THE MINIATURE OF OUR EARTH. 105 

Large series, that I might chart the planet from them. 
Four of his drawings are shown in the accompanying 
plate. They are so selected, that the features just 
coming into view in one are just passing away in the 
next. The accompanying chart of Mars, in which the 
darker parts of the planet are assumed to be seas, and 
the reddish tracts continents, exhibits the results ob- 
tained from the study of the complete series. This 
chart is on the stereographic projection, and is inverted 
— the south polar regions, that is, are at the top — be- 
cause the telescopes commonly used by observers ex- 
hibit inverted views of the celestial objects.* At the 
top of the map we see the icy region which lies at the 
southern pole of Mars. Around that region is a sea un- 
named in the map. Then along the southern temperate 
zone there lie several tracts of Martial land, named 
after Cassini, Lockyer, and other astronomers. These 
regions appear to form a continuous land-belt round 
the temperate zone ; though there is some uncertainty 
on this point, owing to the fact that the coast-line is 
not often very distinctly visible. We now approach, 
however, a part of the map where all the features are 
thoroughly recognized and permanent. Next to the 
circle of land just described, there is a nearly complete 
circle of water, one strip only of land connecting the 
equatorial continents of Mars with the south-temperate 
zone of minor continents. Beginning at the eastern 
or left-hand extremity of the map, we have a long sea, 

* Mr. Browning, F. R. A. S., has formed a globe of Mars from my 
chart, and publishes an interesting series of photographs of this globe 
which give fine stereoscopic effects. 



lo6 OTHER WORLDS THAN OURS. 

called Maraldi Sea, parallel to which runs Hooke Sea, 
trending in a northwesterly direction, and so running 
into Dawes Ocean; still farther west are two vast 
islands, called Jacob Island and Phillips Island, be- 
tween which runs Arago Strait. Beyond these islands 
lies Delarue Ocean, communicating by narrow straits 
with two strikingly similar seas. Here the zone of 
water ends, and we have only to note further, respect- 
ing it, that in Delarue Ocean there is a large island, 
which presents so strikingly brilliant an aspect that it 
has been supposed to be covered (ordinarily) with 
snow. It has been called Dawes's Ice Island. 

I now come to the most remarkable feature of the 
Martial geography — or perhaps I ought rather to say, 
areograjphy. This is the great equatorial zone of 
continents. There are four of these. On the left of 
the map is Herschel I. Continent. Next is Dawes 
Continent, the largest of the four, and separated from 
the former by a long sea called Kaiser Sea. This sea 
is one of the most striking marks on the planet, and 
has been recognized from the earliest days of telescopic 
observation. It is connected toward the east with a 
flask-shaped sea, somewhat resembling the two which 
lie at the western extremity of the zone of water just 
described. At its northernmost end it turns sharply 
westward, and forms the southern boundary of Dawes 
Continent. Farther west lies Madler Continent, sepa- 
rated from Dawes Continent by a long strait, which 
runs almost directly north and south. Lastly, there is 
Secchi Continent, separated from Madler Continent 
by Bessel Inlet and from Herschel Continent by 



MARS, THE MINIATURE OF OUR EARTH. 



107 



Huo;onns Inlet. A large lake on the last-named con- 
tinent is worthy of notice on account of its singular 
shape. It consists of two bell-shaped seas connected 
by a narrow and sharply-cniwed strait. 

The northern half of Mars has not been so thor- 
oughly examined as the southern, for a reason which 
will presently be mentioned. It is known, however, 
that, in all essential respects, it resembles the southern 
hemisphere. Xext to the equatorial zone of continents 
there comes a zone of water, expanding at one point 
into Beer Sea, and at another into Tycho Sea. Then 
comes a zone of land, called Laplace Land, in which 
lies an enormous lake called Delambre Sea. ]Next is 
a narrow zone of water called the Schroter Sea, and 
so we reach the north-polar ice-cap. 

I have been speaking of the spots on Mars as though 
they undoubtedly represented land and water. But 
many may be disposed to question the evidence we 
have on this point — to ask why the ruddy spots should 
be held to be continents or islands, and the greenish- 
colored markings to be oceans, seas, and lakes. We 
know that, for a long time after the invention of the 
telescope, astronomers called the darker portions of the 
moon, seas. They spoke of the Sea of Serenity, the 
Sea of Crises, the Sea of Humors, and so on, and we 
now know for certain that these duskv regions are not 
seas. It may be asked, therefore, how we can feel 
certain that the dark spots on Mars are oceans. 

At first sight, this question seems a difficult one 
to answer. The most powerful telescopes have been 
directed toward the moon, without affording any sat- 



lo« OTHER WORLDS THAN OURS. 

isfactory information respecting the condition of its 
surface. Mars, therefore, which lies — even under the 
most favorable circumstances — more than one hundred 
and sixty times farther from us than the moon, might 
be thought to be altogether beyond the reach of our 
telescopists — so far, at least, as any knowledge of the 
Martial surface is concerned. But one important dis- 
tinction between Mars and the moon must be careful- 
ly attended to. The surface of the moon is always the 
same — no natural processes seem ever to take place 
over that scene of desolation, though the moon is ex- 
posed to contrasts of temperature, compared with 
which the distinction between the intensest heat of 
our summers and the bitterest cold of our winters 
seems altogether evanescent. But, on Mars, the case 
is certainly different. Whatever opinion we may 
form respecting Martial habitudes, whether we assume 
or not that Mars is the abode of any forms of animal 
life, there can be no question whatever that physical 
processes of change are taking place on a grand scale 
in that distant world. Many evidences of this can be 
at once adduced. We have spoken of the Martial fea- 
tures as constant. They differ, for instance, from the 
markings on Jupiter, which are as changeful as the 
aspect of our April skies. But though the same mark- 
ing may have been* seen by Hooke in 1666, by Maral- 
di in 1720, by Herschel in 1780, by Beer and Madler 
in 1830-'37, and by Dawes in 1852-'65, yet it by no 
means follows that it is always visible when the part 
of Mars to which it belongs is turned toward us. A 
veil is sometimes drawn over it for hours or even days 



MARS, THE MINIATURE OF OUR EARTH. 109 

together. And this veil has nothing to do with the 
distinctness or indistinctness with which our own at- 
mosphere permits us to see the planet. A spot wil] 
be blurred and indistinct when a neighboring marking 
is exhibited with unusual clearness. 

Let ns consider an instance of this peculiarity. On 
October 3, 1862, Mr. Lockyer was observing Mars 
late in the evening. He noticed that a part of Dawes 
Ocean, where it borders on Herschel Continent, was 
hidden from view. In place of the ordinarily dark 
aspect of this region, a faint, misty light, with ill-de- 
tined borders, was observable. As the evening pro- 
gressed, he noticed that the outlines gradually became 
clearer, but, when he gave up observation (at about 
half-past eleven), the white light still continued to 
veil the outline of a part of Dawes Ocean. Now, Mr. 
Dawes observed Mars on the same night, at a quarter- 
past twelve. The drawing which he took at that 
hour shows that the process of clearing up, noticed by 
Mr. Lockyer as being in progress in the earlier part 
of the night, had, by the time Mr. Dawes began work, 
entirely lifted off the veil which concealed the coast- 
line. The remains of the misty light seen by Lockyer 
are still to be detected in Mr. Dawes's drawing, but 
they have passed farther south, and no longer hide 
the shores of Dawes Ocean. 

The Padre Secchi, of the Collegio Eomano, states 
that he has often noticed similar appearances, while 
observing Mars with the fine refractor in the observa- 
tory of that institution. 

But yet another peculiarity of the same sort re 



no 



OTHER WORLDS THAN OURS. 



mains to be mentioned. Mars, as I have said, has his 
winter and summer seasons. Since we know the po- 
sition of the Martial equator upon his surface, we can 
tell what season is in progress in either hemisphere at 
any given time. Now, it has been noticed that, when 
it is winter in one hemisphere, and therefore summer 
in the other, the former hemisphere is nearly always 
hidden from view by just such a veil as I have spoken 
of above. 

I may remark, in passing, that this peculiarity has 
led many observers to form very erroneous impressions 
respecting the distribution of land and water over the 
surface of Mars. Seeing one hemisphere covered for 
weeks together with whitish light, they have con- 
cluded that there are no oceans there ; and if they 
have no other opportunity of observing the planet, 
the mistaken impression remains, and is published to 
the world with all the authority of the observer's name. 

Now, what is this veil which, sometimes for a few 
hours or days, at others for months together, is drawn 
over the features of the Martial globe ? Have we any 
terrestrial analogies, by means of which we may in- 
terpret this phenomenon % 

To answer these questions, let us conceive the 
case of an observer on Yenus, watching our earth. 
Would such an observer always see the features of 
this globe with equal distinctness? When heavy 
masses of cloud are drawn over a wide expanse of 
country — spreading often, as meteorologists record, 
for hundreds and even thousands of miles — can we 
suppose that the astronomer on Yenus could pierce 



MARS, THE MINIATURE OF OUR EARTH. lu 

through the veil ? Since we cannot see the bright 
body of the sun through a dense cloud- veil, we may 
be certain that the observer on Yen us cannot see the 
oceans and continents of our earth when thus cloud- 
shadowed. So far as the cloud-veil extends, the lands 
and seas of this globe would be to hirn, at such a time, 
as though they were not. 

Here, then, we have an argument from analogy 
for supposing that the veil, which from time to time 
conceals the Martial features, may resemble terres- 
trial cloud-banks. Let us next inquire whether there 
is any thing in the behavior of the Martial veil to 
justify this view. 

It is clear that, if we held the concealing medium 
to be of a cloudy nature, the disappearance of the fea- 
tures of the hemisphere which is passing through the 
Martial winter would indicate that in winter the 
Martial skies are more clouded than in summer. We 
know that this is the case on our own earth — that 
fogs and mists, clouds, rain, and snow, are phenomena 
far more frequently observed in winter than in sum- 
mer. We know also why it is so. The cold winter 
air is unable to retain the aqueous vapor continually 
passing into it, and is thus forced to precipitate this 
vapor in one or other of the forms just named. Nor 
can we see any reason why the Martial atmosphere, 
supposing it to resemble our own, should not act in 
precisely the same manner. Thus we recognize, in 
the remarkable seasonal peculiarity above described, 
what seems to be the exact counterpart of processes 
recognized upon the earth. 



112 OTHER WORLDS THAN OURS. 

And tbongli I admit that there is considerable ob- 
jection to the mode of argument I am next going to 
make use of, yet, as it is one which has great weigbt 
with many minds, and is not without its own peculiar 
force, I feel justified in applying it as a subsidiary 
support to the views I am discussing. It is known 
that the peculiarities which characterize terrestrial at- 
mospheric phenomena tend in an important manner 
to mitigate the extremes of summer and winter tem- 
perature. The clouds which hang over our winter 
skies, far from acting to increase the coldness of win- 
ter through their effect in keeping off the sun's rays, 
in reality represent an enormous supply of heat 
brought from warmer parts of the earth, and liberated 
for our benefit as the invisible vapor of water assumes 
the form of cloud or rain. And although these pro- 
cesses are strictly in accordance with natural laws, yet 
we are justified in recognizing them as evidences of 
the beneficence of the Almighty. JSTow, on Mars, we 
may be sure, the winters tend to be far more bitter 
than ours, partly because of his greater distance from 
the sun, but chiefly because of the more marked con- 
trast existing between his various seasons. Hence, if 
there are living creatures on Mars, it can scarcely be 
doubted that an arrangement such as that which pre- 
vails on earth is yet more necessary to the welfare of 
the Martialists. Thus, we derive an argument from 
the a priori consideration of the nature of Martial 
requirements, to favor our interpretation of the phe- 
nomena actually observed. 

Perhaps the reader may be disposed to inquire 



MARS, THE MINIATURE OF OUR EARTH. 113 

whether the clearing up of a portion of the Martial 
disk observed by Lockyer and Dawes admits of inter- 
pretation in a similar way. To this it may be replied 
that, from the observed position of the region in ques- 
tion, the Martial time of day there must have been 
somewhere about noon when Mr. Lockyer began hig 
observations, and about one o'clock in the afternoon 
(according to our terrestrial mode of reckoning) when 
Mr. Dawes observed the planet. It is no uncommon 
thing to see our terrestrial skies clear up soon aftei 
midday; and if the veil which conceals the Martial 
features is really cloudy, this is precisely what hap- 
pened out yonder, forty millions of miles away from 
us, on the day in question. 

I think the reader will at least concede that the 
explanation here given of these peculiarities is more 
natural than one which was put forward some time 
since by an eminent French astronomer. He urged 
that Martial vegetation, instead of being green like 
ours, is red ; hence in the Martial summer the sur- 
face, as seen by us, assumes a ruddy aspect, while the 
wintry hemisphere loses its ruddy tint. According to 
this interpretation, such changes as were noticed by 
Secchi would indicate the sudden blooming forth of 
Martial vegetation over hundreds of square miles of 
the Martial surface. 

To the evidence 1 already dealt with may be added 
that which is afforded by the whiteness of the disk of 
Mars near the edge. Knowing that the parts of 
Liars which thus appear concealed in mist are those 
where it is morning or evening to the Martialists, we 



U4 OTHER WORLDS THAN OURS. 

see a close analogy here to terrestrial relations, since 
our own skies are commonly more moisture-laden in 
the morning and evening than near midday.* 

I may here pause, in passing, to notice under what 
difficulties the observation of Mars is conducted by 
the terrestrial observer. To begin with, the sky must 
be exceptionally clear; and none but the practised 
observer knows how seldom there occurs what is 
called " a good observing night." Then it must be a 
fine day for the Martialists, for clouds over Mars, or 
even an imperfectly clear atmosphere, must produce 
quite as bad an effect in spoiling the definition of 
Martial features as similar phenomena on earth. 
Again, Mars only comes into a favorable position 
once in every two and a quarter years, continuing to 
be well placed for only a few months. Thus it hap- 
pens that, although Mars has been telescopically ob- 
served for more than two hundred years, the actual 
time during which he has been favorably placed for 
observation has been very much less ; and, taking into 
account all the requirements for good definition, it 
may be said that Mars has not been under really ef- 
fective observation for more than a very few days. 

Of course, if we admit that the vaporous envelope 



* In the Popular Science Review for January, 1869, I have indi- 
cated a subsidiary explanation of this peculiarity, founded on the prob- 
able shape of the Martial clouds. For the same reason that, near the 
horizon, our own cumulus clouds seem more closely packed than over- 
head, the Martialists would see a clearer sky overhead than near the 
horizon. It follows, at once, that we should see those parts of the sur- 
face of Mars best which we look upon in a nearly vertical direction, 
that is, the central parts of his disk. 



MARS, THE MINIATURE OF OUR EARTH 115 

which occasionally hides parts of Mars is aqueous, we 
must believe in the existence of oceans upon Mars. 
And, from our knowledge of the appearance of our 
own seas, we should immediately recognize the green- 
ish parts of Mars as the Martial oceans, and look upon 
the ruddy parts as continents. We have seen that 
the behavior of the vaporous envelopes corresponds to 
that of our own clouds and fogs. But it might be 
thought possible that the vapors arise from fluids 
other than water ; that, in fact, a state of things ex- 
ists upon Mars wholly different from that which pre- 
vails upon our own earth. 

Ten years ago it would have been very difficult to 
disprove such an argument as this, however bizarre it 
may seem. But the wonderful powers of the spectro- 
scope have been applied to this question, and there is 
no mistaking the results which have been obtained. 
We must premise that this is hardly a favorable case 
for the application of spectroscopic analysis, which (as 
available to the astronomer) deals most effectively 
with self-luminous objects. Still, there was a possibil- 
ity that the light which comes from Mars might have 
been so acted upon by vapors in the Martial atmos- 
phere, that its spectrum would be affected "in an ap- 
preciable manner. 

Mr. Huggins examined Mars in 1864 without satis 
factory results, but at the opposition of Mars in 1867 hr 
was more successful. In the following description oi 
his most striking observation I epitomize his account : 
On February 14th he examined Mars with a spectro- 
scope attached to his powerful eight-inch refractor, 



H 6 OTHER WORLDS THAN OURS. 

The rainbow-colored streak was crossed, near the or- 
ange part, by groups of dark lines agreeing in posi- 
tion " with Jnes which make their appearance in the 
solar spectrum when the snn is low down, so that its 
light has to traverse the denser strata of our atmos- 
phere." To determine whether these lines belonged 
to the light from Mars or were caused by our own at- 
mosphere, Mr. Huggins turned his spectroscope tow- 
ard the moon, which happened to be nearer the hori- 
zon than Mars, so that the atmospheric lines would be 
stronger in the moon's spectrum than in that of the 
planet. But the group of lines referred to was not 
visible in the lunar spectrum. Hence it was clear that 
they belong to the Martial atmosphere, and not to 
ours. 

I have said that these lines appear in the solar 
spectrum when the sun is shining through the denser 
strata of our atmosphere. Let us consider a moment 
the light which this fact throws on the nature of the 
Martial atmosphere. It must contain at least those 
constituent vapors whose existence in our atmosphere 
causes the appearance of these lines in the solar spec 
trum. Hence there must be some similarity between 
the Martial atmosphere and our own. But we know 
from the researches of the Padre Secchi, that it is the 
aqueous vapor in our air which causes the appearance 
of the lines in question. Hence there must be aqueous 
vapor in the Martial atmosphere. 

This discovery at once justifies the title of the 
present chapter. Let us consider what a number of 
interesting results follow from it. 



MARS, TEE MINIATURE OF OUR EARTE. n 7 

The water in the Martial air must be raised from 
Beas and rivers upon the planet. These, therefore, 
consist of water and not of other fluids. The two 
white spots, then, on the Martial disk are no longer 
doubtful appearances. Before the discovery that water 
exists on Mars, it was perhaps somewhat bold to pro- 
nounce that these spots certainly indicate the presence 
of ice-fields around the Martial poles, resembling those 
which exist around the poles of the earth. Sir Wil- 
liam Herschel, indeed, with that confidence which he 
always showed when he had a trustworthy analogy to 
guide him, came to this conclusion on the strength of 
the correspondence between the changes of the two 
spots and the progress of the Martial seasons. But 
many astronomers felt that there was still room to 
doubt whether we could really speak of the spots as 

"The snowy poles of moonless liars." 

Now, however, we know that they can be no other 
than snow-caps. Nay, if Mars were so far off that we 
could not distinguish these spots, we could yet, on the 
strength of what the spectroscope has taught us, pro- 
nounce confidently that his polar regions must be ice- 
bound. 

Let us proceed a step or two farther. "We have 
seen that there are oceans on Mars ; we know that 
clouds and vapors rise from those oceans and are 
wafted over his continents ; and, finally, we have 
learned that snow falls on the Martial polar regions. 
These things are very interesting in themselves, but 
they indicate the occurrence of processes yet more in- 



n8 OTHER WORLDS THAN OURS. 

teresting. The formation and the dissipation of clouds 
are among the most important of all the processes by 
which Nature arranges and modifies the temperature 
of our earth. The heat of the sun's rays is used up, 
so to speak, in raising aqueous vapor from the surface 
of the ocean. Thus the air is rendered cooler than it 
otherwise would he, and this takes place just where 
coolness is most needed. But the aqueous vapor, once 
raised, is swept by the winds to other regions. So 
long as the air remains warm, the aqueous vapor re- 
mains unchanged ; but, so soon as it has been carried 
to colder regions, it is condensed into the form of cloud 
or mist, and while changing to this form it parts with 
the heat which had turned it into vapor. Thus where 
heat is in excess, it is used up in forming aqueous 
vapor, and where heat is wanted there the aqueous 
vapor distributes it. 

We see, then, that on Mars there exists the same 
admirable contrivance for tempering climates which 
we find on our own earth. 

But let us consider yet another office fulfilled by 
aqueous vapor. It not only serves to convey the heat 
from the warmer parts of the earth to those regions 
where heat is most needed. It forms clouds which 
serve to shelter the earth from the sun's heat by day, 
and to prevent the escape of the earth's heat by night, 
which also, in refreshing rains, " drop fatness on the 
earth." Now, the clouds on Mars are certainly dissi- 
pated in some way, because, as I have said, astronomers 
have repeatedly seen them disappear. And doubtless, 
like our own clouds, they are often dissipated by the 



MARS, THE MINIATURE OF OUR EARTH. u 9 

sun's heat. But we may take it for granted that, like 
our terrestrial clouds, they are also often dissipated by 
fallins: in rain. Thus the Martial lands are nourished 
by refreshing rainfalls ; and who can doubt that they 
are thus nourished for the same purpose as our own 
fields and forests — namely, that vegetation of all sorts 
may grow abundantly ? 

But yet, again, the transit of clouds from place to 
place implies the existence of aerial currents. Clouds 
cannot, indeed, even form and be dissipated without 
occasioning wind-currents ; and it need hardly be said 
that the Martial clouds could not be carried to his 
polar regions, there to fall in snow, unless the atmos- 
pheric currents on Mars were extensive and persist- 
ent. We see, then, that Mars has winds as our earth 
has. Doubtless his trade-winds are less marked than 
ours, because his surface rotates less rapidly than the 
earth's, his globe being much smaller, while his rota- 
tion-period is slightly greater. But he has less need 
for trade-winds, his oceans being so much less exten- 
sive than ours. ISTo Columbus on Mars has ever 
needed the persistent breath of easterly winds to en- 
courage him on his voyage to an undiscovered conti- 
nent. Rather, the intricate navigation of the narrow 
Martial seas would be favored by variable breezes. 
But the great purposes which the circulation of our 
own atmosphere subserves are carried out efficiently 
oat yonder on Mars. The air is cleansed and purified, 
its thermal and electrical conditions are regulated, 
clouds are wafted from place to place ; and, in fine, 
the atmosphere is rendered fit- for all those pur- 



120 OTHER WORLDS THAN OURS. 

poses for which, like our own, it has doubtless been 
created. 

We may trace yet further, however, the results 
which flow from the existence of aqueous vapor in. 
the atmosphere of Mars. "We see the polar snows 
aggregating in the Martial winter and diminishing in 
the Martial summer. And we know that, on our own 
earth, the increase and the diminution of the polar 
snows are processes intimately associated with the 
formation and maintenance of the oceanic circulation. 
Doubtless much yet remains to be done before that 
system of circulation will be fully understood. The 
rival views which have been maintained by Sir John 
Herschel and Captain Maury have served to throw a 
certain air of doubt over the theory of ocean-currents.* 
Eut whether we ascribe the equatorial currents of our 
oceans to the trade-winds with Herschel, or to differ- 
ences of specific gravity with Maury, we see that, in 
the first place, both causes operate in the case of Mars, 
and secondly, that the submarine return currents from 

* If Herschel has completely overthrown Maury's theory that currents 
are altogether due to differences of specific gravity, saltness, and so on, 
Maury has at least been as successful in overthrowing Herschel's theory 
that the currents are due to the trade-winds. A theory more probable 
than either is, I think, that according to which the whole system of 
circulation is set in motion by the continual evaporation going on in 
equatorial seas. Thus, by a process resembling suction, an in-draught 
of cold water is caused, and this water coming from higher latitudes, 
where the earth's eastwardly motion is less, to lower latitudes, -where the 
eastwardly motion is greater, produces the relatively cold and westwardly 
equatorial currents which exist in the Atlantic, Indian, and Pacific 
Oceans. Recent reseaiches into the temperature of the deep sea have 
tended strongly to confirm these views, which I dealt with at some 
length in the Intellectual Observer for May, 18 67. 



MARS, THE MINIATURE OF OUR EARTH. i2 i 

our polar regions must, at any rate, be due to the 
presence of ice in the polar seas. So that undoubtedly 
the Martial oceans, so far as their peculiar conforma- 
tion will permit, are traversed by currents in various 
directions and at various depths. 

Then, lastly, there must be rivers on Mars. The 
clouds which often hide from our view the larger part 
of a Martial continent, indicate a rainfall at least as 
considerable (in proportion) as that which we have on 
the earth. The water thus precipitated on the Martial 
continents can find its way no otherwise to the ocean 
than along river-courses. 

As to the nature of these rivers again, we may form 
conjectures founded on trustworthy analogies. The 
mere existence of continents and oceans on Mars 
proves the action of forces of upheaval and of depres- 
sion. There must be volcanic eruptions and earth- 
quakes, modelling and remodelling the crust of Mars. 
Thus there must be mountains and hills, valleys and 
ravines, water-sheds and water-courses. All the various 
kinds of scenery which make our earth so beautiful 
have their representatives in the ruddy planet. The 
river courses to the ocean, by cataract and lake, here 
urging its way impetuously over rocks and bowlders, 
there gliding with stately flow along its more level 
reaches. The rivulet speeds to the river, the brook 
to the rivulet, and from the mountain recesses burst 
forth the refreshing springs which are to feed the 
Martial brooklets 

Who can doubt what the lesson is that all these 
things are meant to teach us ? So far, let it be re- 



l2 2 OTHER WORLDS THAN OURS. 

membered, we have been guided onward by no specu- 
lative fancies, but simply by sober reasoning. But 
can we pause just here % Shall we recognize in Mars 
all that makes our own world so well fitted to our 
wants — land and water, mountain and valley, cloud 
and sunshine, rain, and ice, and snow, rivers and lakes, 
ocean-currents and wind-currents, without believing 
further in the existence of those forms of life without 
which all these things would be wasted ? Surely, if 
it is rashly speculative to say of this charming planet 
that it is the abode of life — if we must, indeed, limit 
ourselves to the consideration of what has been abso- 
lutely seen — it is yet to speculate ten thousand times 
more rashly to assert, in the face of so many probable 
arguments to the contrary, that Mars is a barren 
waste, either wholly untenanted by living creatures, or 
inhabited by beings belonging to the lowest orders of 
animated existence. 



CHAPTER V. 

JTJPITEE, THE GIANT OF THE SOLAR SYSTEM. 

Passing- over the zone of asteroids, we come now 
tc the noblest of all the planets — the giant Jupiter. If 
bulk is to be the measure of a planet's fitness to be 
the abode of living creatures, then must Jupiter be 
inhabited by the most favored races existing through- 
out the whole range of the solar system. Exceeding our 
earth some twelve hundred and thirty times in volume, 
and more than three hundred times in mass, this mag- 
nincent orb was rightly selected by Brewster as the 
crowning proof of the relative insignificance of the 
earth in the scale of creation — assuming only that we 
can indeed gauge the purposes of the Creator by the 
familiar tests of measure and weight. 

Or if we estimate Jupiter rather by the forces in- 
herent in his system, if we contemplate the enormous 
rapidity with which his vast bulk whirls round upon 
its axis, or trace the stately motion with which he 
sweeps onward on his orbit, or measure the influences 
by which he sways his noble family of satellites, we are 
equally impressed with the feeling that here we have 



124 OTHER WORLDS THAN OURS. 

the prince of all the planets, the orb which, of all others 
in the solar scheme, suggests to us conceptions of the 
noblest forms of life. 

The very symmetry and perfection of the system 
which circles round Jupiter have led many to believe 
that he must be inhabited by races superior in intelli- 
gence to any which people our earth. The motions 
of these bodies afford indeed to our astronomers a no- 
ble subject of study. Our most eminent mathemati- 
cians have given many hours of study to the phenome- 
na which the four moons present to the terrestrial ob- 
server. But we can trace only the general movements 
of the satellites of Jupiter. Their minor disturbances, 
the effects of the varying influences which the sun and 
Jupiter exert upon them, and which the moons exert 
upon each other, must tax the powers of far abler 
mathematicians even than he who " surpassed the 
whole human race in mental grasp." 

But, after all, we must judge of Jupiter rather ac- 
cording to the evidence we have, and the analogies 
which are most directly applicable to the case, than 
according to fancies such as these. We know that 
the sun, which surpasses Jupiter in weight and vol- 
ume even more than Jupiter surpasses the earth, is 
yet not the abode of life, so that mere size and mass 
must not be held to argue habitability. We know 
that many meteors and comets sweep through spaces 
more swiftly than the vast bulk of Jupiter, so that the 
energies indicated by mere velocity of motion, whether 
orbital or rotational, must be equally disregarded. 
"Nor must we forget that, ages before men studied the 



JUPITER, GIANT OF THE SOLAR SYSTEM. ^5 

motions of our own moon, she presented the same 
noble subject of study that she forms in our day for 
an Adams, a Leverrier, or a Delaunav. Even now a 
thousand grand problems are presented to our men of 
science which escape their notice ; and we might as 
reasonably argue that there must be creatures existing 
unperceived among us, who deal with these problems, 
as that, out yonder in space, there must be beings 
who study the complicated motions of the Jovial 
satellites. 

Jupiter presents the following principal physical 
habitudes : 

He has a diameter of about eighty-five thousand 
miles, or nearly eleven times as large as the earth's, a 
surface one hundred and fifteen times larger, and, as I 
have said, a volume more than twelve hundred times 
larger. Gravity at his surface is about two and a half 
times as great as on our earth's, so that such creatures 
as exist around us would find their weight much more 
than doubled if they were removed to Jupiter. He 
lies more than five times farther from the sun than 
our earth, and the light and heat which he receives 
from that orb are reduced to about one-twenty-fifth of 
our supply. He rotates on his axis in rather less than 
ten hours (nine hours, fifty-five minutes, twenty-six 
seconds), so that the length of his day is considerably 
less than half of ours. His axis is nearly perpendicu- 
lar to his orbit, so that there are no appreciable sea- 
sonal changes as he sweeps round the sun in his long 
year of 4,332^- days. 

It will be convenient to consider, first, the proba- 



i 2 6 OTHER WORLDS THAN OURS. 

ble influence of the great attractive power of Jupiter 
upon the dimensions of the various orders of living 
creatures existing upon his surface. 

The grandeur of his orb naturally suggests, at first 
sight, the idea of beings far exceeding, both in might 
and bulk, those which live upon the earth. Old 
Wolfius was led to a similar conclusion in another 
way. I quote his quaint fancies as quaintly presented 
by Admiral Smyth. " Wolfius," says the genial sailor, 
" not only asserts that there are inhabitants in Jupiter, 
but also shows that they must necessarily be much 
larger than those of the earth ; in fact, that they are 
of the giant kind, and nearly fourteen feet high by 
^-measurement. And thus he proves it. It is 
shown in optics, that the pupil of the eye dilates and 
contracts according to the degree of light it encoun- 
ters. Wherefore, since in Jupiter the sun's meridian 
height is much weaker than on the earth, the pupil 
will need to be much more dilatable in the Jovial 
creature than in the terrestrial one. But the pupil is 
observed to have a constant proportion to the ball of 
the eye, and the ball of the eye to the rest of the 
body ; so that, in animals, the larger the pupil the 
larger the eye, and consequently the larger the body. 
Assuming that these conditions are unquestionable, 
he shows that Jupiter's distance from the sun, com- 
pared with the earth's, is as twenty-six to five ; the 
intensity of the sun's light in Jupiter is to its intensity 
on the earth in a duplicate ratio five to twenty-six." 
The eyes of the Jovials and their dimensions generally 
must be correspondingly enlarged, and " it therefore 



JUPITER, GIANT OF TEE SOLAR SYSTE2I. l2 y 

follows that even Goliath of G-ath would have cut but 
a sorry figure among the natives of Jupiter. That is, 
supposing the Philistine's altitude to be somewhere 
between eight feet and eleven, according as we lean 
to Bishop Cumberland's calculation, or the Vatican 
copy of the Septuagint. E"ow, Wolfius proves the 
size of the inhabitants of Jupiter to be the same as 
that of Og, king of Bashan, whose iron camp-bed was 
nine cubits in length and four in breadth — or rather 
he shows, in the way stated, the ordinary altitude of 
the Jovicolse to be 13 T y^. Paris feet, and the height 
of Og to have been 13|f f|- feet. See his Works, vol. 
iii., p. 438." 

This exact determination of the dimensions of 
Jovial men would be very pleasing and satisfactory, 
were it not that another line of argument guides us at 
least as conclusively to a very different view. If we 
are to assume that beings resembling men in all attri- 
butes except size, actually exist on Jupiter, we might 
claim for these beings the power of moving from place 
to place as freely as we do, with quite as much reason 
as Wolfius claimed for them the same powers of vis- 
ion that we possess. Proceeding according to this 
view, we are led to the conclusion that the Jovicolm 
are pygmies about two and a half feet, on the average, 
in height. For we know that a man removed to Jupi- 
ter would weigh about two and a half times as much 
as he does on our own earth. He would thus be op- 
pressed with a burden equivalent to half as much 
again as his own weight. This would render life it- 
Belf an insupportable burden ; and we have to inquire 



l2 8 OTHER WORLDS THAN OURS. 

what difference of size would suffice to make a Jove- 
man as active as our terrestrial men. ]STow, the weight 
of "bodies similarly proportioned varies as the third 
power of the height ; for example, a body twice as 
high as another — in other respects similar — will be 
eight times as heavy. But the muscular power of ani- 
mals varies as the cross-section of corresponding mus- 
cles, or obviously as the square of the linear dimen- 
sions ; so that of two animals similarly constituted, 
but one twice as high as the other, the larger would 
be four times the more powerful. He would weigh, 
however, eight times as much as the other. He would 
therefore be only half as active. Similarly, an animal 
three times as high as another of similar build, would 
be only one-third as active ; and so on for all such 
relations. JSTow, since a terrestrial man removed to 
Jupiter would be two and a half times as heavy as on 
the earth, it follows obviously that a man on J upiter 
proportioned like our terrestrial men would be as ac- 
tive as they are, if his height were to theirs as one to 
two and a half. Hence, setting six feet as the maxi- 
mum ordinary height of men on the earth, we see that 
the tallest and handsomest of the Jovicolse can be but 
two and a half feet in height, if only our premises 
are correct. Thus, Tom Thumb and other little fel- 
lows, if removed to Jupiter, might be wondered at for 
their enormous height, and eagerly sought after by 
any Carlylian Fredericks who may be forming grena- 
dier corps out yonder. 

One line of argument having thus led us to regard 
the Jovicolse as Ogs of Bashan, while another equally 



JUPITER, GIANT OF THE SOLAR SYSTEM. 



129 



plausible has reduced their dimensions to those of our 
two-year-old children, we may fairly conclude that 
this method of reasoning is fallacious. "We must not 
measure the inhabitants of other worlds according 
to the conceptions suggested by the forms of life we 
are acquainted with upon earth. We must admit the 
possibility that arrangements, as different from those 
we -are familiar with as the constitution of the insect 
is from that of , man, may be presented amid the orbs 
which circle round the sun. It were unwise, no doubt, 
to give free scope to speculation where we have in 
truth mo means of forming an opinion. We need not 
imagine, as some have done, that " the inhabitants of 
Jupiter are bat-winged," or with others, " that they 
are inveterate dancers." Nor, to take the views of 
more respectable authorities, need we agree with Sir 
Humphry Davy, that the bodies of the Jovials are 
composed of " numerous convolutions of tubes more 
analogous to the trunk of the elephant than any thing 
else ; " with Whewell, that they are pulpy, gelatinous 
creatures, living in a dismal world of water and ice 
with a cindery nucleus ; nor finally, with Brewster, that 
the Jovial may have his " home in subterranean cities 
warmed by central fires, or in crystal caves cooled by 
ocean-tides, or may float with the Nereids upon the 
deep, or mount upon wings as eagles, or rise upon the 
pinions of the dove, that he may flee away and be at 
rest." So soon as we give a definite form to the con- 
ceptions that the imagination, free from the control of 
exact knowledge, frames respecting the inhabitants of 

other worlds, we touch at once on the grotesque, the 
9 



l3 o OTHER WORLDS THAN OURS. 

hideous, or the ridiculous.* It is sufficient to recog- 
nize the probability, or rather the certainty, that the 
beings of other worlds are very different from any we 
are acquainted with, without endeavoring to give 
shape and form to fancies that have no foundation in 
fact. 

We may regard it as probable, however, that living 
creatures in Jupiter, if any exist, are built generally 
on a much smaller scale than those which people our 
earth. Trees, plants, and the vegetable world gener- 
ally, must also, one would imagine, be very differently 
constituted from those we are familiar with. It is well 
known that the motion of the vegetable juices is in 
part regulatepl by the force of gravity, and therefore 
it must be admtited that the structure of terrestrial 
plants is in part dependent upon the value of gravita- 
tion at the earth's surface. Whewell, in his " Bridg- 
water Treatise " on the astronomical evidence of design 
in Creation, lays great stress on this relation, pointing 

* It may be worth while to gather a lesson from this circumstance. 
We know that every form of life is replete with evidences of adaptation 
(no matter how secured) to the conditions which surround it. We have 
thus evidenced to us, as forcibly as possible, the perfection of the laws 
by which the Creator rules the universe, and a measure (if one may so 
speak) even of that which is inconceivable by us — His infinite wisdom. 
Now, man, with all his knowledge of the Creator's ways, yet so soon as 
he passes the boundary of the known, pictures to himself all manner of 
unnatural and impossible forms of existence. Even the unknown parts 
of our own earth have been peopled ere now, in imagination, with " men 
whose heads do grow beneath their shoulders," and other similarly in- 
congruous beings. It is more excusable, perhaps, that an anatomically 
impossible structure should have been assigned to angels (the cherubim 
Lave been even more unfortunate), while the Evil One, that " goeth about 
as a roaring lion," has had the principal attributes of a class of ruml 
navtia assigned to him. 



JUPITER, GIANT OF THE SOLAR SYSTEM. i$\ 

out, if I remember right, that all vegetation would be 
destroyed at once if there could suddenly take place 
any marked change in the earth's attractive forces. 
If this view is correct, it is certain that none of our 
plants could thrive on the soil of Jupiter. 

The year of Jupiter differs in a much more striking 
manner than that of Mars from our terrestrial year. 
It consists of nearly twelve such years as ours, so that 
the period corresponding to one of our seasons lasts 
nearly three years, and a Jovial month is nearly equal 
to one of our terrestrial years. He has, however, no 
seasons in our sense of the word, since his equator is 
inclined but little more than three degrees to his orbit. 
Thus a perpetual spring reigns all over his surface. 

But before we proceed to form a high opinion of 
the planet's condition under the influence of this 
perpetual spring, let us distinctly understand what the 
words mean. The word spring has a genial sound to 
ourselves, because we associate it with that which is 
commonly the pleasantest portion of our year ; but it 
is just possible that the perpetual spring reigning over 
Jupiter, though, doubtless well adapted to the wants 
of his inhabitants, leads to a state of things such as we 
might not find altogether so agreeable. 

Admiral Smyth says that " as the rays of the sun 
fall perpendicularly on the body of the planet,* and 

* In the same paragraph Admiral Smyth says that, as seen from 
Jupiter's equatorial regions, the sun would seem to move through the 
heavens with great rapidity, while near the polar regions the sun's 
^notion will be comparatively slow, and he will be seen to describe only 
a small semicircle above the horizon. The direct reverse is, however, 
the case, the sun's path and the rapidity of his apparent diurnal motion 



132 



OTHER WORLDS THAN OURS. 



always continue to do so, the heat must be as nearly 
as possible equal at all times of the year — a perennial 
summer: this is a striking display of beneficent ar- 
rangement." But we must be cautious in adopting 
this mode of argument in dealing with the Creator's 
ways. That the arrangement is beneficent, we need 
not of course question. But that we can recognize 
the way in which it is beneficent is quite another mat- 
ter. If Jupiter's great distance from the sun is com- 
pensated for by this peculiar disposition of his axis, 
and we are to admire the beneficence thus displayed, 
are we therefore to find fault with the Creator for 
not dealing similarly with Saturn, Uranus, and Nep- 
tune, which, being farther from the sun, have greater 
need than Jupiter of some special adaptation of the 
sort ? It seems safer to consider the consequences 
which flow from the arrangement without any special 
reference to the design of the Creator in permitting 
them, lest, in our over-anxiety to recognize beneficence 
in the treatment of one world, we should adopt a 
mode of reasoning which leads to the direct conclu- 
sion that other worlds have been ill-cared for. 

being nearly constant for all parts of Jupiter, and throughout his year. 
Admiral Smyth seems to have thought that the variations of the sun's 
path in Jupiter corresponded to those observed in the progress of a year 
at any place on the earth's equator, the sun always rising vertically 
and always describing a complete semicircle, though attaining different 
altitudes at different seasons. The real fact is, that in all parts of 
Jupiter the sun describes a complete diurnal semicircle, attaining a 
different midday altitude in different places. But, as he always rises 
nearly due east, and sets nearly due west (as he does in spring-time aU 
over the earth), he necessarily crosses the horizon at different angles as 
seen in different places, and always describes about half of a great 
circle of the spheie. 



JUPITER, GIANT OF THE SOLAR SYSTEM. 



l 33 



The great peculiarity resulting from the arrange- 
ment in question — the only peculiarity, in fact, of 
which we can speak with any confidence — consists in 
this, that, everywhere on Jupiter,- day and night are of 
equal length. It is in this sense only that perpetual 
spring — or perpetual autumn, if we please — reigns on 
the giant planet. The different latitudes of Jupiter 
have climates differing quite as much as those found 
in different latitudes on our own earth. At the 
equator the sun passes every day nearly to the point 
overhead. At the poles the sun seems to glide along 
the horizon, rising in the east, passing round — always 
near the horizon — toward the south, and thence to 
his setting-place in the west. In intermediate lati- 
tudes, the sun passes to a southerly elevation which is 
greater or less, according as the place is nearer to or 
farther from Jupiter's equator. It follows that there 
is a marked difference between the sub-equatorial and 
the sub-polar regions in Jupiter, while between these 
regions every intermediate climate is to be found. 

Owing to the rapidity of Jupiter's rotation, the 
motion of the sun in the Jovial sky must be much 
more readily discernible and measurable than that 
with which the sun seems to pass across our own 
heavens. He traverses the whole semicircle, from the 
eastern to the western horizon, in two minutes less than 
five hours, or about six degrees in ten minutes. This 
corresponds to a motion through a space equal to the 
sun's diameter (as we see him) in fifty seconds, and 
must be readily discernible, even to the unaided vision 
of the Jovicolse, unless their eyesight is much infe- 



!34 OTHER WORLDS THAN OURS. 

rior to ours. The smallness of the sun, as seen from 
Jupiter, must help to render the motion more percep- 
tible. He presents to them an apparent diameter only 
equal to about one-fifth of that with which we see 
him, so that in ten seconds he seems to pass over a 
space equal to his own diameter. 

The other celestial bodies are affected with similar 
motions as seen from Jupiter. Of course, those seen 
near the poles of his heavens seem relatively at rest. 
One of these poles lies in the heart of the constellation 
Draco ; the other lies close by the great Magellanic 
Cloud, which must present a magnificent cynosure to 
the inhabitants of the southern hemisphere of the 
planet. The contrast between the steadfastness of 
the polar star-groups and the swift motions of the 
equatorial constellations, must be impressive indeed. 
These equatorial groups are no other than our old 
friends the zodiacal constellations. As seen by the 
inhabitants of Jupiter, they rise with a perceptible 
but stately motion above the eastern horizon, pass to 
their culmination on the southern meridian, and so to 
their setting-place in the west — exhibiting the same 
splendors which the terrestrial astronomer delights to 
gaze upon, enhanced by the peculiar impressions of 
active power suggested by visible and obvious motion. 

It may seem, at first sight, that the presence of the 
Jovial satellites must tend to dim the splendor of the 
sidereal heavens. Our own moon, despite the beauti- 
ful passage * in which Homer has described the calm 

* Homer must not be held responsible for Pope's amazing description, 
which, strangely enough, has found an ardent admirer in one of our 



JUPITER, GIAXT OF THE SOLAR SYSTEM. 135 

beauty of a moonlit night, certainly detracts largely 
from the magnificence of the star-groups ; and as at 
times there must be four moons visible above the 
horizon of the Jovials, it might seem that all but the 
brighter stars would be quite obliterated. The first 
moon must appear somewhat larger than our own ; 
the next has an apparent diameter rather more than 
half as large as that of our moon ; the third (really 
the largest) appears about as large as the second ; and 
the fourth has an apparent diameter equal to about a 
quarter of our moon's. Thus, in all, they cover a 
6pace on the sky more than half as large again as that 
which our moon covers. But, in reality, they cannot 
have nearly so marked an effect in dimming the lus- 
tre of the stars. For it must not be forgotten that 
they shine only by reflecting the sun's light, and that 
he illuminates them but faintly, in comparison with 
the light he pours upon our own moon. In effect, 
supposing their reflective capacities equal to the 
moon's, they must appear less brilliant than she does, 
in the proportion of about one to twenty-five; and 
combining this result with the above relation, it fol- 
lows that, even if they could all be "full" together, 
they could send to the Jovials but about one-sixteenth 
part of the light we receive from the full moon. But, 
as a matter of fact, they cannot all be full together. 
The motions of the inner three are so related, that, 
though there is nothing to prevent them from being 

best modern observers. Homer did, however, mention as a character- 
istic of the moonlit sky, that " all the stars shine," a proof that soma 
times, as Horace tells us, the great master nodded. 



136 OTHER WORLDS THAN OURS. 

all visible together,* yet when so visible, one only can 
be full. The fourth may be full at the same time, or, 
in fact, may De combined with the other three in any 
way, since its motions are not bound up with theirs as 
theirs are inter se. 

Even now, however, we have not reached a full 
estimate of the extent of the mistake which those as- 
tronomers have made who speak of the splendor with 
which the satellites of Jupiter illuminate his skies. 
When at that part of their orbits where they would 
otherwise be full, the three inner moons are always 
eclipsed, and though the fourth, by reason of its great 
distance,f sometimes escapes eclipse, yet more fre- 
quently it is obscured like the others. The two inner 
satellites are eclipsed for upward of two hours, and as 
they occupy but a few hours in completing their cir- 
cuit round the sky, $ it will be seen how largely this 
relation detracts from their light-supplying powers. 

We see, then, that those writers have been mis- 
taken who allege that the great distance of Jupiter 
from the sun is compensated by the number of his 
moons, and the quantity of light they reflect toward 
him. So far is this from being the case, that, under 
the most favorable circumstances, they can supply 

* Or all invisible together. Lardner asserts the contrary ; so that 
one would imagine he had never seen all the moons together on the 
same side of Jupiter. 

\ Not on account of the inclination of its orbit being large, as Sir 
John Herschel has said. The orbit of this satellite is, mdeed, less in- 
clined than the orbits of the others. 

% Moving in a direction contrary to that due to the rotation of 
Jupiter, they of course remain longer above the horizon than the sun, 
or the equatorial fixed stars. 



JUPITER, GIAXT OF THE SOLAR SYSTEM. 337 

during the Jovial night "but about one-twentieth part 
of the light with which the full moon illunainates our 
nocturnal skies. The poetical descriptions which im- 
aginative writers have indulged in, respecting the 
splendor of the scene presented by these satellites, 
will not bear the dry light of numerical estimation. 
That the satellite-system of Jupiter subserves impor- 
tant functions, and affords, in reality, like all the 
works of the Creator, the amplest evidence of design, 
need not be questioned ; but that we have been able 
to understand the special purpose for which they have 
been created — in fine, " to see," as the Creator does, 
" that they are good " — may be assuredly denied. 

Perhaps, if one were able to discuss with advan- 
tage the special purposes which this or that portion 
of creation is intended to subserve, it might be argued 
that the outer planets have greater need of moons 
than the inner, because, their year being longer, there 
is greater occasion for objects whose motions shall 
serve as measures of time. The satellites of Jupiter 
supply, by their separate motions, convenient meas- 
ures of the shorter time-intervals ; while, by their suc- 
cessive conjunctions, (i.) in pairs, (ii.) the three inner 
together, and (iii.) the outer with pairs of the inner, 
they afford convenient measures of longer intervals. 

But let us turn from vague guesses at the purposes 
of the Almighty, to the consideration of those facts 
which are actually presented to our notice. 

Recognizing the existence of varied climatic rela- 
tions in different parts of Jupiter, we have now tc 
consider the climate of the planet generally, to con- 



,38 OTHER WORLDS THAN OURS. 

template the position of this great orb in the solar 
system, and to determine how far its great distance 
from the snn may be compensated by other relations. 

There can be no doubt that the amount of heat 
poured by the sun on any portion of Jupiter's surface, 
placed perpendicularly with respect to the heat-rays, 
must be very much less than the amount received by 
an equal portion of our earth's surface, similarly situ- 
ated. The direct heating effects of the sun must, in 
fact, as already stated, be less on Jupiter than on our 
own earth, in the proportion of about one to twenty- 
five. And it cannot be doubted that the effects of 
this difference must be highly important, whatever 
arrangements may exist to compensate for the defi- 
ciency of heat. If we can demonstrate in any way 
that the mean temperature of the Jovial atmosphere 
is equal to that of our own air, or even greater, yet 
the difference of the sun's direct heat involves a variety 
of consequences which we cannot disregard. 

We know, for instance, that it is principally the 
direct heat of the sun that causes the evaporation of 
water from the surface of oceans, seas, lakes, and riv- 
ers, and therefore all the important consequences 
which flow from the presence of aqueous vapor in large 
quantities in the earth's atmosphere. We can con- 
ceive the existence of vapors in the air which might 
keep away from the earth's surface the greater portion 
of the sun's heat, and yet, by preventing the escape 
of the remainder by radiation into space, might leave 
the general warmth of the air around us as great as it 
is at present. But it cannot be doubted that such an 



JUPITER, GIANT OF THE SOLAR SYSTEM. iffi 

arrangement would injuriously affect the whole econ- 
omy of evaporation and its consequences, winds, rains, 
clouds, mist, with their consequences, so important for 
the welfare of terrestrial races. 

And in like manner other effects accruing from the 
direct action of the solar rays might be considered. 

It follows, then, that it is by no means sufficient to 
show how the heat which falls upon Jupiter may be 
stored up, through the action of some component of 
his atmosphere in preventing its radiation into space. 
It is, indeed, of the utmost importance to know that 
even this is possible, because we are thus enabled to 
see that Jupiter is not necessarily an abode so bleak 
and desolate as some writers have imagined. In the 
following passage, Prof. Tyndall has exhibited the 
means by which this result may be brought about, 
and the inhabitants of the noblest planet in the solar 
system placed somewhat higher in the scale of crea- 
tion than Whewell surmised. " In these calculations," 
he remarked, referring to "WTiewell's estimate of the 
sun's heating power on Jupiter and the other exterior 
planets, " the influence of an atmospheric envelope was 
overlooked, and this omission vitiated the entire argu- 
ment. It is perfectly possible to find an atmosphere 
which would act the part of a barb to the solar rays, 
permitting their entrance toward the planet, but pre- 
venting their withdrawal. For example, a layer of 
air, two inches in thickness, and saturated with the 
vapor of sulphuric ether, would offer very little re- 
sistance to the passage of the ether rays, but I find 
that it would cut off fully thirty-five per cent, of the 



' 4 o 



OTHER WORLDS THAN OURS. 



planetary radiation. It would require no inordinate 
thickening of the layer of vapor to double this ab- 
sorption ; and it is perfectly evident that, with a pro- 
tecting envelope of this kind, permitting the heat to 
enter but preventing its escape, a comfortable tem- 
perature might be obtained on the surface of our 
most distant planet." The difference between such 
an arrangement as this and the way in which the 
earth's temperature is obtained, is the exact converse 
of that dealt with when we were considering the case 
of Mercury and Yenus. Precisely as the mean tem- 
perature of the atmosphere of either of the interior 
planets may be no higher than that of our own air, 
while yet the sun's direct rays continue wholly un- 
bearable, so the outer planets may have a perfectly 
comfortable temperature, while yet that direct solar 
heat which exerts so many important influences on the 
earth must be supplied only in quantities which we 
should find wholly inadequate for our wants. 

I am far from desiring to infer that Jupiter must 
therefore be uninhabited, or even that the creatures 
existing on his surface must necessarily differ wholly 
in their nature from any with which we are familiar. 
But I think that, while, on the one hand, we must 
reject one of the chief arguments by which "Whewell 
was led to people Jupiter with cartilaginous and gluti- 
nous creatures (!) floating in boundless oceans, so, on 
the other, we cannot accept without question the ar- 
gument by which an effort has been made to indicate 
the possibility of a close correspondence between Jupi- 
ter's climate and our earth's. 



JUPITER, GIANT OF THE SOLAR SYSTEM. i + 1 

And here we are led to the most interesting and 
suggestive of all the relations exhibited by Jupiter, or 
rather to three closely-associated relations, which lead 
to views of a somewhat startling character. 

In common with the other large planets lying out- 
side the zone of the asteroids, Jupiter has a mean 
density falling very far short of the mean density of 
the earth or the other small planets which travel with- 
in that zone. According to the best estimates of his 
mass and apparent diameter, his mean density would 
seem to be rather less than one-fourth of the earth's, 
or greater than the density of water by about one- 
third. It is worthy of remark, in fact, that his den- 
sity is almost exactly the same as the sun's, and con- 
siderably greater than that of the other three outer 
planets hitherto discovered. 

If we were quite certain that the disk measured by 
us exhibits the real outline of the planet, or that his 
atmosphere was not of abnormal extent, and that his 
globe was solid throughout, it would follow that the 
substances composing Jupiter were either altogether 
different from those forming our earth, or that they 
were combined in very different proportions. On the 
last point we can form no opinion. On the first we 
must be guided by the appearance of the planet. 

Thus we are led to the second ol the three rela- 
tions just mentioned — the appearance of well-marked 
but variable belts on the planet — and of other indica- 
tions implying the existence of an atmosphere of great 
extent. 

The belts of Jupiter are commonly arranged with 



l 4 2 OTHER WORLDS THAN OURS. 

a certain symmetry on either side of the great equa- 
torial bright belt, but sometimes there is a rather 
marked contrast between the northern and the south- 
ern halves of the planet. In color the dark belts are 
usually — when seen with suitable telescopic power * — 
of a coppery, ruddy, or even purplish tint, while the 
intermediate light bands -vary from a pearly white in 
the equatorial belt, through yellowish white in the 
middle latitudes of both hemispheres, to a grayish or 
even bluish tint at the poles. The picture of Jupiter 
which forms the frontispiece, while exhibiting many 
of the features usually seen, is intended specially to 
illustrate relations presently to be dealt with. 

There is every reason to believe that these belts 
indicate the existence of a very extensive vapor-laden 
atmosphere. The dark belts must not be considered 
as the true cloud-belts, because it must be remembered 
that we look upon the reverse side of the skyscape 
presented during the day to the Jovials : so that 
where they see densely-compacted dark clouds, we see 
the light which those clouds have intercepted ; and, on 
the other hand, where they see clear spaces, the light 
which reaches them is not reflected to us without a 
considerable loss of brilliancy. Thus the dark belts 

* What is required is not so much a high light-gathering as a high 
magnifying power, though both points are of importance. When the 
light is not adequately reduced by increase of magnifying power, the 
color is lost in the resulting " glare." Eeflectors seem to have an ad- 
vantage over refractors in exhibiting the colors of the planets ; at least, 
nearly all the accounts in which the appearance of color has been spe- 
cially dwelt upon, have been received from observers who have used 
reflectors. 



JUPITER, GIANT OF THE SOLAR SYSTEM. 



H3 



af Jupiter are those regions where — if at all — we see 
the true surface of the planet. 

Now, viewing the belts in this light, have we any 
means of judging from their aspect what is the extent 
of the planet's atmosphere? So far as I know, the 
question has never been considered, but it is well 
worthy of careful study. 

It seems clear, in the first place, that if the bright 
belts really are cloud-belts, and the dark belts the sur- 
face of the planet, then on the edge of the planet's 
disk we ought to see some irregularity of level — the 
cloud-belts projecting slightly beyond the real out- 
line of the planet — if the atmosphere have that enor- 
mous extent which some astronomers have supposed. 
Whether such an appearance has ever been looked for 
I do not know, but it has certainly never yet been 
detected. 

We are forced to conclude, then, that either the 
atmosphere of Jupiter is not sufficiently extensive to 
interfere appreciably with our measurement of the 
planet's bulk, or else the dark belts belong but to a 
lower cloud-layer, not to the planet's real surface. 

We have further evidence on this point in the ap- 
pearance of dark spots on the dusky belts. These 
spots have even been described as black, though surely 
their appearing of that hue must be ascribed to the 
effect of contrast. Now, these dark spots, which have 
been seen by Cassini, Madler, Schwabe, Airy, and 
others, may be regarded as the real surface of the 
planet (unless they belong to a yet deeper cloud-layer), 
Been for a while through openings in the cloud-bed to 



! 44 OTHER WORLDS THAN OURS. 

which the dusky belts belong. The reader will not 
fail to notice here some resemblance to what has been 
already mentioned respecting the sun-spots ; and when 
we come to the third and most striking of the associ- 
ated features I am now dealing with, it will be seen 
that there may be more in the analogy than one might 
at first sight be disposed to imagine. 

How far the appearance of small round white spots 
on the dark belts may be considered as indicative of 
the extent and constitution of the Jovial atmosphere, 
it is not very easy to determine. That they are dense 
clouds, hanging suspended above the dusky cloud- 
layer, must be admitted as highly probable, but it is 
open to question whether they have formed there in 
the same way that cirrus-clouds are seen to form at a 
great elevation above a layer of cumulus clouds, or 
whether they indicate the action of volcanoes beneath 
the dusky layer, propelling enormous streams of vapor 
through the superincumbent cloud-beds. 

The third point on which I have to dwell is the 
variability of the belt-system, under which head I in- 
clude not only variations in shape and extent, but 
those much more significant changes of color which 
have been recently discovered. 

So far as is yet known, there is no recognizable 
law in the changes of shape exhibited by the belts of 
Jupiter — no periodicity or intelligible sequence. It 
may be suggested, in passing, that a systematic and 
persistent scrutiny of the planet might lead to the dis- 
covery of laws of this sort, which could not fail to in- 
dicate physical conclusions of the utmost imDortance. 



JUPITER, GIANT OF THE SOLAR SYSTEM. i 4 c 

N"ay, further, since we cannot doubt that the condition 
of the real surface of Jupiter is in some sort reflected, 
so to speak, in the aspect of his cloud-envelopes, it 
seems far from unlikely that a scrutiny of this sort 
might tell us where his oceans and continents, where 
his deserts, lakes, or rivers, are situated, even though 
no direct evidence of their existence might ever reward 
the observer. In these days, however, nine-tenths of 
those who are fortunate enough to possess fine tele- 
scopes prefer either to leave them idle, or to employ 
their powers in making observations, at great pains 
and labor, which are not worth the paper on which 
they are recorded.* The few original observers we 
have are overtasked by the multitude of questions of 
interest presented to their consideration, so that many 
subjects of inquiry must perforce wait, either till their 
turn arrives, or till those who have the means of 

* It is painful to those who know what might be done in the numer- 
ous fine observatories now existing throughout England, to see the 
powers of many noble instruments — the chef-d'ceuvres of English and 
Continental opticians — devoted to puny imitations of the work done at 
Greenwich and other similar establishments. I speak on the authority 
of one of the first, if not the very first, of our professional astronomers, 
when I say that these imitations, even though they approached in char- 
acter — which they do not and cannot — the operations superintended so 
ably by the Astronomer Royal, would be a simple waste of time and 
labor. Nor is this the only way in which fine telescopes are wasted. 
While on every side there are subjects of research which most pre s&ingij 
require investigation, many of those who possess the requisite means 
and leisure for the purpose — nay, are not wanting in the necessary taste 
for observational research — are unhappily applying themselves to going 
over, perhaps with relatively inferior powers, ground which has already 
been thoroughly ransacked by our great observers. With some ten or 
twelve exceptions — which it is unnecessary to name — our private ob> 
aervatories seem to have banished every thing resembling originality. 
10 



146 OTHER WORLDS THAN OURS. 

studying them choose to turn their thoughts from the 
sterile subjects they are now engaged upon. 

So far, then, as inquiries have as yet been pushed, 
all that can be asserted on the subject we are consid- 
ering is, that the planet's belts vary greatly in form, 
extent, and general appearance. At one time the 
dusky belts cover a large proportion of the planet's 
disk, at another they are singularly narrow. Now 
they are very regularly disposed, now they seem in 
some way under the action of disturbing forces of 
great intensity, causing them to assume the most ir« 



Fm. l.— The Planet Jupiter (Browning). 

regular figure. The accompanying picture ot the plan 
et (Fig. 1) as seen by Mr. Browning, with one of his 



JUPITER, GIANT OF THE SOLAR SYSTEM. x ^ ? 

own reflectors, indicates an appearance not uncom- 
monly seen, a dark streak extending obliquely across 
the planet's equatorial regions. The number of belts 
is singularly variable. Sometimes only one has been 
a een, at others there have been as many as live or six 
on each side of the planet's equator. In the course of 
a single hour, Cassini saw a complete new belt form 
on the planet, and on December 13, 1690, two well- 
marked belts vanished completely, while a third had 
almost disappeared in the same short interval of time 
But if we seem to recognize here the action of 
forces much more intense than those which influence 
the condition of the earth's atmosphere, we have still 
more striking evidence to the same purpose in the 
changes of color which have recently been detected in 
the great equatorial belt. This belt is usually of a pearly 
white tint, and has long been recognized as one of the 
most constant features of the planet's aspect. As the 
mean surface of this belt cannot be less than a fifth of 
the whole surface of the planet, it is clear that any 
changes which may take place in its general aspect can- 
not but be of the utmost significance. ISTow, during the 
autumn of 1869 and the spring of 1870, this belt has 
been more strongly colored than any part of the 
planet. Mr. Browning (to whom I am indebted for the 
beautiful painting of Jupiter, which formed the design 
fiom which the frontispiece has been taken), observing 
Jupiter in the earlier part of the above-named interval, 
found the equatorial belt of a greenish-yellow color, 
which deepened in October, 1869, to a full ochreish 
yellow, and in January of the present year had assumed 



I4 8 OTHER WORLDS THAN OURS. 

an even darker tint, resembling yellow ochre. On one 
occasion, and on one only, he detected this tint in the 
first bright belt north of the equator. While thus ex- 
hibiting strongly-marked and changing colors, the 
equatorial belt has lost its right to be called, par ex- 
cellence, the bright belt of the planet, being consider- 
ably inferior in brilliancy to the narrow bright belts 
north and south of it. 

Other observers have also seen these colors. Mr. 
Slack, with a 6-inch Browning- With reflector, and 
Mr. Brindley, with an 8|-inch telescope of the same 
construction, have witnessed most of the changes of 
color above described ; and I myself, using Mr. 
Browning's 12^-inch telescope, found the greenish- 
yellow tint of the equatorial belt last autumn altogether 
unmistakable.* 

In the phenomena here described we have a prob- 
lem whose interpretation is far from easy. Changes in 
the shape, disposition, and extent of the dark belts are 
sufficiently intelligible when we associate them, as we 
seem justified in doing, with variations in the position 
of the currents which traverse the vaporous envelope 
of Jupiter as the trades and counter-trades traverse 
the earth's atmosphere. But the equatorial zone is 
Jupiter's belt of calms, resembling in this respect the 
equatorial region, called by sailors the " doldrums," 

* I had written thus far only, when I attended the meeting of the 
Royal Astronomical Society on January 14, 18V0, where Mr. Buckingham, 
the owner of the great refractor, 21^ inches in aperture, from whose per- 
formance so much was expected, mentioned that, as seen with thia 
powerful instrument, the great belt was resolved into a number of small 
solored clouds on a white ground. 



JUPITER, GIANT OF THE SOLAR SYSTEM. ^ 

and, though occasional storms might be expected to 
agitate this region, yet processes of change, continuing 
for several months in succession, can evidently not be 
attributed to any such cause. We are taught, by the 
progress ot recent research, to regard the color of 
the light derived from any source as a relation of the 
most instructive character, and changes of color, 
especially changes affecting so enormous a body as 
Jupiter, and so extensive a proportion of his surface, 
cannot but be looked upon as highly significant. Sup- 
posing we regard the ordinarily white light of the 
equatorial belt as indicative of the existence of 
enormous masses of cloud reflecting ordinary solar 
light to us, then we should have to regard the appear- 
ance of anv other color over this region as an indica- 
tion that these cloud-masses had been, through some 
unknown cause, either wholly or in part swept away. 
But — passing over the objection that this view leaves 
our difficulty unexplained — even if we assumed that in 
this way a portion of the surface of Jupiter had been 
brought into view, wholly or partially, why should this 
surface not exhibit a constant appearance ? We cannot 
suppose changes affecting Jupiter's real surface are 
taking place with sufficient rapidity to explain the 
series of strange color-changes observed by Messrs. 
Browning, Slack, and other astronomers. But if, on the 
other hand, we assume that a portion of the light ordi- 
narily received from the bright belt is inherent — that 
is, that the planet is, to some extent, self-luminous- 
then there remains the difficulty of explaining by what 
conceivable processes the equatorial regions are filled 



i 5 o OTHER WORLDS THAN OURS, 

with a yellow light, so full and bright as to reach our 
earth from beyond four hundred millions of miles. 

But I have spoken of the three relations last con- 
sidered — the small density of Jupiter, his extensive at- 
mosphere, and the changes which take place in the 
shape and color of his belts — as associated phenomena. 
It remains that I should endeavor to justify this state- 
ment. 

"We know that Whewell, reasoning from the low 
specific gravity of Jupiter, was led to the conclusion 
that either the substance of the planet is wholly watery, 
or else a few cinders in the centre of Jupiter's globe 
constitute the only sdid portion of his substance. It 
need hardly be said that the whole progress of modern 
astronomy is opposed to this view. We have seen 
that in the sun the same elements exist as in the earth, 
and that in the only planet whose nature we have been 
able to examine satisfactorily we find evidence of the 
existence of the same forms of matxci that we see 
around us. It cannot but be held as highly improb- 
able that the earth is the only member of the planetary 
system whose substance thus closely resembles that of 
the parent orb, nor is it likely that Mars is the only 
planet whose general atmospheric constitution resem- 
bles the earth's. Far more probably the lesson we 
are really to learn from these circumstances is, that 
throughout the solar system a general similarity of 
constitution exists, the sun being, so to speak, the 
type of the family over which he rules. Differences 
of condition we are compelled to recognize, since the 
sun itself, though constituted of the same elements as 



JUPITER, GIANT OF THE SOZA.R SYSTEM. nj , 

tlie earth, is in so different a state and has a mean 
density relatively so small ; but we have no evidence 
justifying us in believing that any important differ- 
ences of constitution exist throughout the solar system. 
Thus, we are led to regard the singularly small 
density of Jupiter and of the other planets outside the 
orbits of the asteroids, as due rather to some peculiarity 
in the condition of these orbs than to any such pecu- 
liarity of structure as Whewell insisted on. It will 
be seen at once that Jupiter's extensive atmospheric 
envelope and the strange changes in the aspect of his 
belts are circumstances which tend strikingly to confirm 
this impression. Let it be remembered that, supposing 
Jupiter's globe even to be wholly covered with water, 
yet a sun twenty-five times farther off than ours could 
not by any possibility load his atmosphere with the 
enormous masses of vapor actually present in it. Let 
it be remembered, further, that the relatively slug- 
gish action of the sun upon Jupiter could not by any 
possibility give rise to atmospheric disturbances so tre- 
mendous as those which are evidenced by the rapid 
changes of figure of his cloud-bands.* When to this 

* It is worthy of consideration, also, that even though the sun acted 
as efficiently upon the air and oceans of Jupiter (assumed to be similar 
to our own), yet atmospheric disturbances (due chiefly, as we know, to 
these two forms of action) could not possibly be so violent even as on 
our own earth, since corresponding latitudes of Jupiter (that is, regions 
where corresponding effects would be experienced) are separated by 
distances so very much greater. It is clear that, if along a certain zone 
of a planet the sun exerts a certain amount of influence, while along 
another he exerts a different influence, the result of the difference, 
tooked on as a cause of atmospheric disturbance, must be smaller as the 
distance between the zones is greater. 



152 OTHER WORLDS THAN OURS. 

we add tlie relative minuteness of the seasonal changes 
on Jupiter, we see at once that, unless some other cause 
than solar action were at work, the condition of Jupi- 
ter's atmosphere ought to be very much calmer than 
that of the earth's. 

It seems to me that these considerations point with 
tolerable clearness to the conclusion that, within the 
orb which presents so glorious an aspect upon our 
skies, processes of disturbance must be at work wholly 
different from any taking place on our own earth. 
That enormous atmospheric envelope is loaded with 
vaporous masses by some influence exerted from be- 
neath its level. Those disturbances which take place 
so frequently and so rapidly are the evidences of the 
action of forces enormously exceeding those which 
the sun can by any possibility exert upon so distant a 
globe. And if analogy is to be our guide, and we 
are to judge of the condition of Jupiter according 
to what we know or guess of the past condition of the 
earth and the present condition of the sun, we seem 
led to the conclusion that Jupiter is still a glowing 
mass, fluid probably throughout, still bubbling and 
seething with the intensity of the primeval fires, 
sending up continually enormous masses of cloud, to 
be gathered into bands under the influence of the swift 
rotation of the giant planet. No otherwise, as it seems 
to me, can one explain the intense vitality, if one 
may use the expression, of a planet circumstanced as 
Jupiter is. No otherwise can one understand whence 
his atmosphere is loaded with vapor-masses whose 
contents must exceed, on a moderate computation, all 



JUPITER, GIANT OF THE SOLAR SYSTEM. 1$3 

the oceans on the surface of this earth. "When we see 
masses so enormous swayed by influences of such 
energy, that intermediate belts, thousands of miles in 
width, are closed up in a single hour ; * when we recog- 
nize the tremendous character of the motions which, 
from beyond four hundred millions of miles, are dis- 
tinctly cognizable by our telescopes, we see that we 
have no ordinary phenomena to deal with, and that the 
theory we adopt for their explanation cannot be other- 
wise than striking and surprising. 

If the view which I have here put forward — or 
rather, the view to which I have been led by a careful 
consideration of the phenomena which Jupiter presents 
to our contemplation — be indeed correct, we must of 
course dismiss the idea that the giant planet is at pres- 
ent a fit abode for living creatures. Yet need we not 
turn from his system with the thought that here at 
least our hopes of recognizing other worlds have been 
disappointed. If Jupiter be still in a sense a sun, not 
indeed resplendent like the great centre of the planet- 
ary scheme, but still a source of heat, is there not ex- 
cellent reason for believing that the system which cir- 
cles around him consists of four worlds where life — 
even such forms of life as we are familiar with — may 
still exist ? Those four orbs, which our telescopes re- 
veal to us as tiny points of light, are in reality globes 
which may be compared with the four worlds that 

* Even if we take the disappearance of a dark belt to be due to the 
formation of clouds, which is perhaps more probable than that the clouds 
of neighboring belts have closed in, the forces represented by the change 
are nevertheless tremendous. 



i 5 4 OTHER WORLDS THAN OURS. 

circle nearest to the sun. I have shown that they can- 
not subserve the purpose which many astronomers 
have ascribed to them, of compensating Jupiter for 
the small amount of light he receives, even if they 
could be seen from any point of his cloud-encom- 
passed surface. So that, even adopting the common- 
place and superficial view that the purpose of any ob- 
ject may be regarded as ascertained when we have 
been able to ask (without any obvious answer) what 
other purpose it can subserve, we still are led to the 
belief that the satellites of Jupiter must be the abode 
of life, since on this view, and on this view only, we 
find a raison d'etre both for the planet and for the sys- 
tem which circles round him. 

There are no considerations which appear directly 
opposed to the view that Jupiter is in a sense a sun. 
It need hardly be said that I do not regard him as 
being in the same condition as the central luminary 
of the planetary system. He is not an incandescent 
body, or, if he is, the greater part of his light is veiled 
by the cloud-envelopes which surround him. The 
solar clouds are, as we know, themselves luminous; 
those of Jupiter are not so, a circumstance which 
indicates that the heat of Jupiter is not sufficient 
to vaporize those substances which are incandescent 
when in the liquid state. The outer layer of clouds 
must, therefore, be regarded as for the most part 
aqueous. We see there, in fact, the future oceans of 
Jupiter, if the hypothesis I am now dealing with be 
correct. 

That Jupiter may supply an immense amount of 



JUPITER, GIANT OF TEE SOLAR SYSTEM. 155 

heat to his satellites (on this view of his condition) is 
perfectly clear, since the amount of light he emits is 
no adequate measure of the amount of obscure heat 
which radiates from him to the four worlds around 
kim. When we consider the enormous apparent size 
of Jupiter as seen from his satellites, we recognize at 
once how large a supply of heat he is capable of trans- 
mitting to them. From the outermost satellite his 
apparent diameter exceeds that of the sun (as seen by 
us) some eightfold, and his apparent size, therefore, 
exceeds the sun's more than sixtyfold. From the 
innermost he is seen with a diameter nearly forty times 
that of the sun, and with an apparent area more than 
fourteen hundred times as large as his. 

We have evidence, however, which renders it far 
from improbable that Jupiter may emit some small 
proportion of light. I have already referred to the 
singular excess of his brilliancy over that due to his 
size and his distance from the sun and from us. The 
estimates of Zollner, the eminent photometrician, serve 
to show, not, indeed, that Jupiter sends more light to 
us than he receives from the sun, but that he sends 
much more light than a planet of equal size and con- 
stituted like Mars, the moon, or the earth, could possi- 
bly reflect to us if placed where Jupiter is. Whereas 
Mars reflects but one-fourth of the light he receives, 
Jupiter reflects more than three-fifths. The moon sends 
less than a fifth ; Saturn, Jupiter's brother giant, more 
than a half. The late Prof. Gr. Bond, of America, act- 
ually calculated that Jupiter sends forth more light 
than he receives. Whether his observations or the 



I 5 6 OTHER WORLDS THAN OURS. 

more systematic observations of the German astron- 
omer are accepted, we see that, unless we adopt some 
such hypothesis as I have dealt with above, we must 
recognize a marked difference between the relative 
light-reflecting capacities of the two largest planets of 
the system, and those of Mars or the moon. In fact, 
from other researches of Dr. Zollner's it follows that, 
if Jupiter do not shine in part by native light, his sur- 
face must possess reflective powers nearly equal to those 
of white paper. Now, this would scarcely be credible, 
even though under the telescope the planet's surface 
were found to be universally white ; but, as we find a 
large proportion of it to be of a dull coppery hue, we 
seem forced to admit that it cannot really have an av- 
erage reflective power nearly so great as that calculated 
by Zollner. It follows, as at least highly probable, 
that Jupiter shines in part by his own light, and this 
being admitted, we cannot but regard it as highly 
probable that the mass of the planet must be intensely 
hot. 

It may seem, at first sight, that the apparent black- 
ness of the satellites' shadows, as seen on the disk of 
Jupiter, is wholly opposed to the view that any por- 
tion of his light is native. But, as a matter of fact, 
there is no force at all in this consideration, or rather, 
whatever weight we may attach to the observed ap- 
pearance of the satellites' shadows is in favor of the 
strange theory here put forward. For it has been a 
subject of remark among the most experienced ob- 
servers, that a satellite in transit will occasionally ap- 
oear as dark as its shadow, both seeming black. The 



JUPITER, GIANT OF THE SOLAR SYSTEM. i$ 7 

Diaekness, then, is only apparent, and an effect of con- 
trast. In reality, if such observations as I have men- 
tioned are to be trusted (and I know no reason for dis- 
regarding them), the shadow of a satellite is not black, 
and therefore there seems no escape from the conclu- 
sion that the surface on which they are projected is 
partially self-luminous. 

A stronger argument against the belief that Jupi- 
ter is self-luminous, lies in the fact that the satellites 
disappear in his shadow. It must be remembered, 
however, that in any case we can assign but a small 
proportion of inherent light to Jupiter, and that his 
satellites would, therefore, in any case, lose so large a 
proportion of their light when passing into his shadow, 
that we might expect them to disappear, even under 
the closest telescopic scrutiny. 

Although I have already far exceeded the limits 1 
had proposed to myself for the consideration of this 
noble planet, it is with regret that I take leave of him 
to pass onward to the outermost bounds of the solar 
system. I would fain dwell even longer than I have, 
on a subject of contemplation at once so interesting 
and so instructive. Jupiter, the centre of a noble sys- 
tem of worlds, or Jupiter, himself a world, inhabited 
by beings as high perhaps in the scale of creation as 
he himself is in the scheme of the planets, is alike a 
worthy subject of study. The more one dwells on the 
features he presents, the more one is impressed with 
the sense of the grandeur of his position in the uni- 
verse. Surely, whether now inhabited or poy, he 
must be intended to be one dav the abode of noble 



l 5 8 OTHER WORLDS THAN OURS. 

races. Surely no astronomer worthy the name can 
regard this grand orb as the cinder-centred globe of 
watery matter so contemptuously dealt with by one 
who, be it remembered thankfully, was not an as- 
tronomer. He who has not gazed hour after hour on 
the glories of the giant planet, gathering fresh delight 
as feature after feature is revealed beneath his scru- 
tiny — he who takes his astronomy but at second-hand 
from the pages of the real worker, turning from la- 
bors in other fields " to see what these star-gazers have 
to say," may lightly disregard the grand lesson which. 
the heavens are always teaching, and find only the 
grotesque and the incongruous, where in reality there 
is the perfectest handiwork of the Creator. But the 
astronomer, imbued with the sense of beauty and per- 
fection which each fresh hour of world-study instils 
more deeply into his soul, reads a nobler lesson in the 
skies. The music which reaches his ears may be 
fitful, but it is not " as sweet bells jangled out of tune 
and harsh ; " he may not master its full meaning, 
though every note thrills through his inmost soul ; 
but, even when its sounds are least distinct, they have 
a beauty and solemnity which are all their own. In 
fine, the true astronomer may say with the Pythago- 
rean, but in another sense : 

" There's not one orb which thou behold'st 
But in his motion like an angel sings, 
Still quiring to the young-eyed cherubim ; 
But while this muddy vesture of decay 
Doth grossly close us in we cannot hear it." 



CHAPTEE VI. 

SATURN I THE KINGED WOELD. 

If Jupiter by his commanding proportions affords 
a forceful argument against the view that our tiny 
earth is the only real world in the solar system, Sat- 
urn supplies an argument of scarcely inferior strength 
in the singularly complex character of the scheme of 
which he is the centre. No one can contemplate this 
glorious planet, as shown by a telescope of adequate 
power, without being impressed by the conviction that 
he is looking at a world altogether more important in 
the scheme of creation than the globe on which he 
lives. Whether he recognizes in the present condi- 
tion of the planet the result of the action of those 
laws which the Almighty has assigned to His uni- 
verse, or whether he prefers the view that Saturn and 
his system are seen now as they were fashioned at the 
beginning by the Almighty's creative hand, he is 
alike amazed at the wealth of design exhibited in the 
scene he is gazing upon. He may not be able, in- 
deed, to appreciate the true character of the purposes 
which the various parts of the Saturnian system are 



160 OTHER WORLDS THAN OURS. 

intended to subserve, or he may, in the rash attempt 
to solve the mighty problem, be led to erroneous con- 
ceptions; but that the great planet is designed for 
purposes of the noblest sort, he cannot gravely ques- 
tion.* 

In volume and mass Saturn is inferior to Jupiter. 
Jupiter is twelve hundred and thirty times, Saturn is 
not quite seven hundred times as large as the earth ; 
and, while Jupiter outweighs her three hundred times, 
Saturn is scarcely ninety times as heavy as she is. 
Still Saturn is sufficiently large and massive to dwarf 
our earth to insignificance; and even Uranus and 
Neptune, though belonging to the family of the 
major planets, and giants compared with the earth, 
fall below Saturn far more than he does below Ju- 
piter. 

Like Jupiter, Saturn rotates very rapidly on his 
axis, the length of his day being about 10^ of our 
hours. The materials of which Saturn is composed 
have a mean density not much greater than half that 
of Jupiter, or less than three-fourths of the mean den- 
sity of water. In fact, Saturn's substance is specific- 
ally lighter than that of any known planet. It seems 
not impossible that we have in this relation some in- 
dication of the true cause of that complexity of detail 
which the Saturnian system exhibits. 

The equator of Saturn is inclined about 28-J- de- 

* I know nothing better calculated to lead men to choose astronomy 
as their favorite subject of study, than the contemplation of the Satur- 
nian system. I can well remember the sensations with which — some 
eight years since? — I saw the ringed planet for the first time. I look on 
'.hat view as my introduction to the most fascinating of all the sciences, 



SATURN: THE RINGED WORLD. 161 

gjrees to the plane in which the planet moves, so that 
his seasons (so far as they depend on this circum- 
stance) closely resemble in character those of the plan- 
et Mars. fe occupies about 29 j- years in circling 
once round the sun — this therefore is the length of the 
Saturnian year. His distance from the sun is nearly 
twice that of Jupiter, and nearly ten times that of the 
earth : so that the amount of lteht and heat which 
any portion of his surface receives from the sun is 
about -^-st part of that received by a similar portion 
of the earth's. His orbit being somewhat eccentric, 
however, there is a considerable variation in this re- 
spect during the course of a Saturnian year, insomuch 
that when he is nearest to the sun he receives more 
light than when in aphelion in the proportion of 
about five to four. 

Most of the relations which have to be considered 
in discussing the habitability of Saturn have been 
already dealt with (under very similar conditions) in 
treating of other planets ; so that I propose to touch 
on them very lightly, in order to come more quickly 
to those circumstances whicb distinguish Saturn spe- 
cially among the other members of the solar system. 

Gravity at his equator is almost exactly equal to 
gravity at the earth's surface. Near the poles there is 
a marked increase in the action of Saturnian gravity, 
insomuch that a body weighing ten pounds at his 
equator would weigh about twelve pounds at either 
pole. There is nothing, however, in this peculiarity 
which need be specially dwelt upon. 

The length of the Saturnian year, and the small 
11 



1 62 OTHER WORLDS THAN OURS. 

quantity of light and heat received from the sun, are 
simply more marked instances of what has already 
been considered in the case of Jupiter. "We may 
conclude with some confidence that these relations are 
quite sufficient to render Saturn wholly uninhabitable 
by such creatures as exist upon the earth ; but there 
seems no reason for supposing that (so far as these 
relations alone are concerned) the planet may not be 
the abode of living beings as high in the scale of crea- 
tion as any which live upon our globe. 

And thus viewing Saturn, we cannot regard even 
the exceptional effects produced by his ring-system as 
of themselves sufficient to banish life from his surface. 
These effects are not without interest, however, and, as 
they have been made the subject of some discussion, I 
may be permitted to make a few remarks upon them. 

I apprehend that, when Sir John Herschel said 
that the rings occasion an eclijDse of nearly fifteen 
years in duration, first to the northern and then to 
the southern hemisphere of the planet, he meant sim- 
ply that during an interval of such length a large por- 
tion oi either hemisphere was in shadow. He knew 
perfectly well that, lonp; after the edge of the ring 
has been turned directly toward the sun, a very large 
proportion of the hemisphere, over which the ring's 
shadow proceeds to sweep, remains illuminated. It 
had always seemed to me, therefore, altogether a mis- 
take on the part of Dr. Lardner to interpret Herschel's 
words as though implying that a whole hemisphere of 
the planet is eclipsed for fifteen years in succession. 

So misinterpreting the expression used by Sir John 



SATURN: THE RINGED WORLD. ^ 

Herschel, Dr. Lardner, in his desire to show that no 
such relation existed, was led into real mistakes which 
a sounder mathematician would not have fallen into, 
He examined the relations presented by the ring in a 
^^-mathematical, but inexact manner, and came to 
the following conclusions : ; ' That, by the apparent mo- 
tions of the heavens produced by the diurnal rotation 
of Saturn, the celestial objects, including the sun and 
the eight satellites, are not carried parallel to the 
edges of the rings ; that they are moved so as to pass 
alternately from side to side of these edges ; that, in 
general, such objects as pass under the rings are only 
occulted by them for short intervals before and after 
their meridional culmination (sic) ; that, although, un- 
der some rare and exceptional circumstances and con- 
ditions, certain objects — the sun being among the 
number— are occulted from rising to setting, the en- 
durance of these phenomena is not such as has been 
supposed, and the places of their occurrence are far 
more limited." All these statements are more or less 
incorrect, and most of them are the direct reverse of 
the truth. The seven inner satellites of Saturn stand 
in an altogether different relation, with respect to the 
rings, than all other celestial objects, since they travel 
in the same plane and in circles concentric with the 
outlines of the rings : they can, therefore, no more be 
occulted by the rings, than an outer ring can be 
occulted by an inner one. So far is it again from be- 
ing true that the sun is in general only occulted for a 
short time before and after culmination, that the more 
common case (considering the whole planet) is for the 



164 OTHER WORLDS THAN OURS. 

sun to be eclipsed (if at all) throughout the whole of 
the Saturnian day ; and a very common case, left al- 
together unnoticed by Dr. Lardner, is, that the sun is 
occulted in the forenoon and afternoon, but free from 
eclipse in the middle of the day. Nor is it true that 
the places where the sun can be totally eclipsed 
throughout the day are limited to a relatively small 
portion of the planet, since every part of the planet 
whence the rings are visible at all has the sun eclipsed 
by the rings throughout the whole day for a longer or 
shorter succession of rotations, and, in the remaining 

7 7 O 

or polar regions of the planet, the sun is altogether 
absent for long intervals of time, for the same reason 
that he is absent from the skies of our. polar regions 
during a comparatively short interval. As for the 
endurance of the total diurnal eclipses, it is only ne- 
cessary to remark that, in Saturnian latitudes corre- 
sponding to that of London or Paris, the sun is totally 
eclipsed for more than five years in succession, while 
in a latitude corresponding to that of Madrid he is 
totally eclipsed for nearly seven years in succession. 
This suffices to show that an arrangement which the 
inhabitants of earth would find wholly unendurable 
prevails over a very large proportion of Saturn's sur- 
face.* 

* The views here expressed as to the effects of the Saturnian rings 
are founded on exact mathematical calculation, of which the elements 
are given in my treatise on Saturn. The problem is not by any means 
a difficult one, and the only way in which the erroneous views formed 
by Dr. Lardner can be explained is, by considering that he dealt with 
the problem in a general instead of an exact manner. I could not feel 
any doubt as to the accuracy of my results, but I was not the less 
pleased to receive a letter from Mr. Freeman, a Fellow of St. John's 



SATURN: THE RINGED WORLD. L 6 5 

But, if we consider the matter rightly, we shall see 
that this, after all, need not surprise us, since there is 
already in the enormous distance of Saturn from the 
sun the amplest reason for believing that he canuo? 
be inhabited by such creatures as exist upon the earth. 
It is in vain that, by conceiving him to be surrounded 
by a dense atmosphere, we assign to him a mean 
climate as warm as that of the earth. The want of 
direct solar heat still remains, and must be regarded 
as a fatal objection to the habitability of Saturn by 
races resembling those with which we are familiar. 

In the case of Saturn as in the case of Jupiter, the 
provision of satellites, and of the rings which form 
so glorious an object to the astronomer on earth, is 
altogether inadequate to increase the supply of light 
received by the Saturnians to any such extent as has 
been imagined. Those well-meaning persons who 
insist on their own interpretation of the Almighty's 
designs, are singularly successful in overlooking very 
obvious difficulties. If the design of the rings, for in- 
stance, really were to compensate the Saturnians for the 
small amount of light which they receive from the sun, 
it would surely follow that there was a want of wisdom 
in the selection of an arrangement by which more light 
is kept away from Saturn than the rings can possibly 
reflect to him. And further, during the very season 
when the extra light derived from the rings is most 
required by the planet, that is, during the long nights 

College, Cambridge, stating that he had obtained similar results, and 
had constructed a table on the plan of Table XI. in my "Saturn," and 
so closely according with it as not to need separate publication. 



166 OTHER WORLDS THAN OURS. 

of the Saturnian winter, they exhibit a dart band upon 
the heavens, concealing whole constellations from the 
view of the Saturnian people. As far as the satellites 
are concerned, there is no corresponding difficulty. 
They undoubtedly reflect the sun's light to Saturn, 
and, if there really are intelligent beings on the planet, 
the satellites must undoubtedly present an interesting 
spectacle, especially when a large number of the moons 
are nearly full. But a little consideration will show 
that, even though all the satellites were full at the same 
time, the quantity of light they could send back to 
their primary would be wholly inadequate to com- 
pensate for the planet's great distance from the sun. 
According to the best estimates of their magnitude, the 
eight satellites, taken in their order from the planet, 
cover spaces on the Saturnian heavens which bear to 
the space covered by our moon the respective propor- 
tions of about 2, 1, 1J, f, -f, -J, y^-, ■£$. In all, then, 
they cover an area about six times that of our moon ; 
and as, owing to their great distance from the sun, they 
are illumined by only j^oth of the light which illu- 
minates our moon, they could only send back to the 
planet, if it were possible for them to be all full 
together, about -^th part of the light we receive from 
the full moon. It will be remembered that the light 
which could be reflected from the Jovial moons, if they 
could be all full together, bears about the same propor- 
tion to our moon's. We seem forced to the conclusion 
that the satellites were intended to subserve no such 
design as has been imagined. Here, as in many other 
eases, the scheme of the Creator is not so obvious 



SATURN: THE RIXGED WORLD. 167 

to human reasoning as some have complacently sup- 
posed. 

But we have now to consider peculiarities which 
suggest that Saturn's globe has not jet reached a con- 
dition fitting it to be the abode of living creatures, 
These peculiarities resemble in great part those which 
have been already noticed in the case of Jupiter, but 
a certain most remarkable phenomenon belongs to 
the ringed planet alone. 

The belts of Saturn resemble those of Jupiter in 
their general shape and also in their color — see the ac- 
companying plate. The dark belts near the equator 
are of a faint brown or ruddy tinge, those near the 
pole bluish or greenish gray, while the bright belts are 
yellowish — the equatorial belt being the brightest of 
all and almost white. The poles are commonly dusky 
and even sombre in hue. 

The belts change in aspect much as those of Jupiter 
have been observed to do ; and whether we regard the 
change as due to the bodily transference of the belts of 
cloud or to the precipitation of their material in the 
form of rain (while, elsewhere, invisible vapors are 
condensed into cloud), we are compelled to recognize 
the action of forces altogether exceeding those which 
the sun can be supposed to exert upon this distant 
planet. The light sent to us from Saturn also bears 
a much greater proportion to the amount of solar light 
actually received by the planet than is observed iu 
the case of Mars or the moon, and so nearly ap- 
proaches the proportion noticed in the case of Jupiter 
as to lead to the same inference — namely, that a por- 



i68 OTHER WORLDS THAN OURS. 

t:'on of Saturn's light is emitted from the body of the 
planet. 

In these respects, and also in the small density of 
the planet, we seem to recognize evidence which points 
to Saturn as probably a heat-sun (if not to any very 
noteworthy extent a light-sun) to the satellites which 
circle round him, and not himself the abode of living 
creatures. Without dwelling further on evidence 
already fully considered in the case of Jupiter, I turn 
to one of the most striking facts in the whole range 
cf observational astronomy, as supplying at once new 
evidence respecting the condition of Saturn and 
strengthening the evidence adduced respecting Ju- 
piter. 

If it can be shown that Saturn's globe is subject to 
changes of figure perceptible even across the enormous 
gap which separates him from the earth, it will at once 
be admitted that he can hardly be regarded as a globe 
conveniently habitable. Now, I have very little hesi- 
tation in saying that evidence of the most conclusive 
kind exists in favor of this strange mobility of figure. 
It will presently be seen that it is with the observa- 
tions of no mere amateur astronomers that I have to 
deal in endeavoring to establish as a fact that which 
has commonly been spoken of as an illusion — the as- 
sumption by Saturn of his so-called " square-shouh 
dered " figure. 

It was in April, 1805, that Sir William Herschel 
first called attention to this peculiarity. The planet, 
which had always presented to him an elliptical figure, 
exhibited a strangely-distorted aspect. A well-marked 



SATURN: THE RINGED WORLD. 169 

flattening at the equator, accompanied by an equally 
well-marked flattening at the poles, gave the planet's 
globe an oblong figure (with rounded angles), the 
longest diameters having their extremities in Satur- 
nian latitude 43° 20' — so exactly was the great astron- 
omer able to indicate the nature of the deformity, 
owing to its well-marked character. 

'What view shah we form respecting an observation 
of so remarkable a character ? "Was the peculiarity 
due to telescopic distortion ? Herschel observed it 
with several instruments, some seven, some ten, one 
twenty, and one forty feet in length. Was the phe- 
nomenon clue to atmospheric disturbances ? Such dis- 
turbances could not account for a persistent impres- 
sion, however well they might explain the momentary 
assumption of the square-shouldered aspect by the 
ringed planet. Besides, Jupiter presented no such 
appearance. Was the appearance an optical illusion 
due to the position of the ring — then slightly open ? 
If so, the planet should always exhibit the square- 
shouldered aspect when his rings are open to that par- 
ticular extent ; and this is not the case. Besides, we 
ought to notice a similar illusion, when looking at a 
picture representing that particular phase of Saturn. 
Must we, then, accept the astounding conclusion that 
the giant bulk of Saturn is subject to throes of so tre- 
mendous a nature as to upheave whole zones of his 
eurface five or six hundred miles above their ordinary 
level ? Truly the conclusion is one to be avoided, if 
we can by any possibility find a less startling expla- 
nation of the matter 



)7 OTHER WORLDS THAN OURS. 

Yet where are we to look for such an explanation \ 
Was Sir William Herschel simply deceived ? I have 
already considered the general question of illusion, 
but the reader might entertain the explanation as con- 
ceivable that Herschel might for a while have lost the 
acumen which distinguished him — that illness, for ex- 
ample, might have rendered his observations inexact. 
But we have abundant evidence that the great astron- 
omer was in the full possession of all his wonderful 
powers as an observer during the month of April, 
1805 ; we know further that by careful measurements 
he rigidly excluded all possibility of illusion affecting 
his judgment. 

It would be more satisfactory, doubtless, to the 
reader, however, to learn that other observers had 
noticed similar peculiarities, or peculiarities which, if 
not similar, were at least such as to prepare us to 
regard the globe of Saturn as liable to remarkable 
changes of figure. Fortunately, many such obser- 
vations have been recorded. I take the following 
from one of an admirable series of papers on Sat- 
urn by Mr. "Webb, in the Intellectual Observer for 
1866. 

On August 5, 1803, Schroter found Saturn not 
perfectly spheroidal in figure. Kitchener says that 
for a few months in the autumn of 1818 he saw Saturn 
of the figure described by Sir William Herschel, and 
that with two different achromatics. At this time the 
ring must have appeared too narrow to account for 
the appearance as due to illusion. On one occasion 
the Astronomer Royal had a similar view of Saturn. 



SATURN: THE RINGED WORLD. i?l 

He remarks, also, that a person unacquainted with 
Herschel's observation remarked spontaneously on the 
flattened equator of the planet. On another occasion, 
Mr. Airy noticed the exact reverse, the planet seem- 
ing flattened instead of upheaved, in latitude 45°. In 
January, 1855, Coolidge, using the splendid refractor 
of the Cambridge, U. S., Observatory, noticed that the 
greatest diameter of the globe seemed inclined about 
20° to the equatorial diameter; but on the 9th the 
equatorial diameter seemed the greatest ; while on De- 
cember 6th he says, " I cannot persuade myself that 
it is an optical illusion which makes the maximum 
diameter of the ball intersect the limb half-way be- 
tween the northern edge of the equatorial belt and the 
inner ellipse of the inner bright ring." All this time 
the rings were nearly at their greatest opening, so 
that any illusion should have been of an opposite char- 
acter to that observed when the rings were nearly 
closed. In the report of the Greenwich Observatory 
for 1 860-'61, it is stated that " Saturn has sometimes 
appeared to exhibit the square-shouldered aspect." 
The eminent observers Bond, father and son, have no- 
ticed similar peculiarities, using the great Merzre frac- 
tor already referred to. Each of them noticed a flat- 
tening of the north-polar regions of the planet in the 
summer of 1848, when the ring was turned edgewise 
toward us. On the other hand, the same observers 
noticed that in 1855-'5T, when the ring was most 
widely opened, the polar regions did not always seem 
projected farthest on the outer ring in a symmet- 
rical manner, but four times on the left of the pole, 



172 OTHER WORLDS THAN OURS. 

once on the right, and once only, exactly opposite 
the pole. " The outline of this region also occasion- 
ally appeared irregularly flattened and distorted," an 
appearance not satisfactorily explained by the jux- 
taposition of the dark shadow of the planet on the 
ring. 

Now, there can be no doubt whatever that the 
planet Saturn is not ordinarily distorted. In 1832, 
during the disappearance of the ring, Bessel carefully 
determined the figure of the planet's disk, and Main 
in 1848 (when the ring was again turned edgewise 
toward us) made similar measurements. Each of 
these trustworthy authorities came to the conclusion 
that the disk of Saturn did not, at the seasons when 
they respectively measured it, exhibit any distortion 
of figure such as Herschel had described. 

We seem almost compelled, therefore, to accept 
the conclusion that the planet Saturn is subject to the 
influence of forces which either upheave portions of its 
surface from time to time, or cause vast masses of 
cloud to rise to an enormous height above the mean 
layer of Saturn's cloud-envelope. Whichever view we 
adopt, we cannot fail to recognize the fact that an in- 
tense heat must in all probability prevail in the great 
globe of Saturn ; and doubtless the real mass of the 
planet must emit a brilliant light, though the cloud- 
strata surrounding him may prevent us from recogniz- 
ing more than a minute proportion of his luminosity. 
In fact, according to this view, Saturn and Jupiter, 
unlike the sun, whose real substance emits a less in- 
tense light than the cloud-photosphere surrounding him. 



SATURN: THE RINGED WORLD. 



73 



must have nuclei — solid or liquid — shining with an 
altogether ruore brilliant light than the cloud-envel- 
opes of these planets seem actually to emit. 

Why Saturn, rather than Jupiter, should exhibit 
these mysterious changes of figure, is readily explica- 
ble when we remember the near coincidence of the 
planes in which the Jovial satellites move with the 
orbital plane of their primary. There thus always re- 
sults a close agreement between the zone on which the 
satellites exert their greatest disturbing influences, and 
that most influenced by the solar action. No such co- 
incidence exists in the case of Saturn, whose satellites 
travel in a plane inclined nearly thirty degrees to that 
in which their primary travels. It is worthy of men- 
tion, however, that Schroter, an accurate and practised 
observer, records that on certain occasions he thought 
he could detect partial flattenings of the disk of Ju- 
piter (see also Preface). 

I think the evidence in the case of Saturn favors, 
at least as strongly as that which has been adduced in 
the case of Jupiter, the belief that the giant planets 
outside the zone of asteroids are not themselves 
suitable abodes for living creatures, but are suns, sup- 
plementing the small amount of light, and yet more 
fully supplementing the small amount of heat which 
the sun supplies to the satellites which circle around 
these orbs. Undoubtedly, if we are to judge accord- 
ing to the method which has been so often applied to 
such questions, if we are to ask ourselves according to 
what arrangement the central planets and the schemes 
circling round them seem most reasonably interpreted, 



174 



OTHER WORLDS THAN OURS. 



we should at once adopt some such conclusion. For, 
by taking Jupiter and Saturn to be strictly analogous 
to our own earth, and their satellites to be subsidiary 
bodies, resembling our moon in this, that they sub- 
serve at present no other purpose but to illuminate 
the nocturnal skies and to sway the oceans of their 
primaries, we find ourselves perplexed by the consid- 
eration that a much simpler arrangement would have 
subserved these purposes much more completely. In 
the case of Saturn's satellites, indeed, it seems diffi- 
cult to conceive that these bodies could have been in- 
tended to fulfil any such purposes, since the two outer 
ones could neither give any useful light to their pri- 
mary, nor sway appreciably any oceans which may 
exist upon the planet. 

On the other hand, if Saturn and Jupiter are suns 
to their satellites, we see in the Saturnian and Jovial 
systems real miniatures of the solar system. "We no 
longer require that the planets themselves should be 
habitable, any more than we require that our sun 
should be so. In fine, we do not find in any portion 
of either system that waste of material which per- 
plexes us under the former arrangement. 

I do not say that this mode of reasoning has any 
great force. On the contrary, I am disposed to demur 
to the opinion that it is given to man to assign a rea- 
son for all things which science may reveal to him. 
For reasons which seem to me far more convincing, 
I am led, however, to believe that the two most im- 
portant members of the planetary scheme must be left 
without inhabitants for the present, while in exchange 



SATURN. TEE RINGED WORLD. 175 

I submit to the contemplation of the curious twelve 
small orbs, constituting two miniature world-systems. 
The condition of these worlds will be touched on 
briefly in a separate chapter. 



CHAPTEE VII. 

TTKANUS AND NEPTUNE, THE ARCTIC PLANETS. 

A circumstance which is of great importance in 
considering the relations of the outer planets is apt to 
be lost sight of, owing to the unsatisfactory manner in 
which, in nearly all books on astronomy, the planetary 
orbits are represented. To look at the series of equi- 
distant and concentric circles representing the orbits 
of the planets, who would suppose that, in passing 
from the orbit of Jupiter to that of Saturn, a distance 
five times as great as that which separates our earth 
from the sun has to be traversed ? But the distance 
separating Uranus from Saturn is twice as great even 
as this tremendous gap, while Neptune travels as far 
beyond Uranus as Uranus beyond Saturn. Nine hun- 
dred millions of miles in width is the enormous gap by 
which the path of Uranus is separated from that of the 
ringed planet on the inner side, and from that of dis- 
tant Neptune on the outer, so that a line equal to the 
diameter of Jupiter's orbit would barely suffice to reach 
from Saturn to Uranus, or from Uranus to Neptune, 
even when either pair of planets are in conjunction. 
• We know so little of the physical aspect of Uranus 



URANUS AND NEPTUNE— ARCTIC PLANETS. 177 

and Neptune that it is extremely difficult to form any 
opinion as to their condition. The two planets resem- 
ble each other in size, each being far smaller than 
either of the giant orbs we have lately been consid- 
ering. Uranus has a diameter of about 33,250 miles ; 
Neptune is somewhat larger, his diameter having been 
estimated at 37,250 miles. The volume of Uranus is 
74, the volume of Neptune 105 times that of the 
earth. Both planets exceed Saturn in density ; for, 
whereas Saturn's mean specific gravity is but -j^ths, 
that of Uranus is -j^ths, and that of Neptune -j^-tlis, 
of the mean specific gravity of our globe. Thus each 
planet has a density nearly equal to that of water. 
The mass of Uranus exceeds the earth's about 12 J 
times, while that of Neptune is some 16f times as 
great as the earth's. It will be seen, therefore, that 
though these two far-distant worlds are much less mas- 
sive than Jupiter or Saturn, each of them outweighs 
many times the combined mass of the four planets 
which travel within the zone of asteroids. Yet grav- 
ity on the surface of these two orbs is but about three- 
fourths of terrestrial gravity. 

The disk of the sun as seen from Uranus is less 
than that which we see in the proportion of nearly 390 
to 1, while the Neptunians have a sun only about -j^o-th 
of ours, in apparent size; and in these proportions the 
solar light and heat received by these planets are re- 
spectively diminished. So small does the sun appear, 
in fact, that to eyes such as ours his orb could not 
present a disk-like figure, but would appear like an 
exceedingly brilliant day-star. 
12 



i 7 8 OTHER WORLDS THAN OURS. 

So far we have found the circumstances of the two 
planets somewhat similar. But we have now to con- 
sider a relation presented by Uranus, which is not 
shared in by Neptune. It may be remarked that we 
know so little about either planet that any very care- 
ful consideration of their habitability would be simply 
a waste of labor. The evidence I am about to adduce, 
however, in the case of Uranus, seems thoroughly to 
dispose of the claim of this planet to be regarded as a 
world inhabited by creatures resembling those we are 
acquainted with on earth ; and, as we cannot reason- 
ably suppose Neptune to be inhabited by such crea- 
tures while Uranus is not, we may very fairly regard 
the question as disposed of for both planets, even 
thong) i the relation dealt with is peculiar to Uranus. 

We know that in the case of Jupiter, as in that of 
Saturn, the position of the plane near which the satel- 
lites travel is nearly coincident with the plane of the 
primary's equator. Therefore, though no telescope 
has yet exhibited any features on the disk of Uranus 
which can enable us to determine the position of its 
equator, we can reasonably infer from the motion of 
the satellites how the equator of the planet is situated. 

Now, the satellites of Uranus travel in a plane very 
nearly at right angles to the plane in which the plan- 
et travels. It may be mentioned also, though not im- 
portant for my present purpose, that they travel in a 
retrograde direction. We conclude, then, that the axis 
of Uranus lies very nearly in the plane wherein the 
planet moves around the sun, and that the planet ro- 
tates iu such a way around this axis that the sun 



URAXUS AND NEPTUNE— ARCTIC PLANETS. i 7g 

moves across the Uranian skies from west to east, in- 
stead of from east to west. The latter relation is of no 
great importance; the former, however, involves re- 
sults which dispose at once, and thoroughly, of any 
hopes we might entertain of discovering creatures in 
Uranus resembling those which inhabit the earth. 

The inclination of the plane of Uranus's equator 
to the path in which he travels being about 76 degrees, 
it follows that the Uranian sun has a range of about 76 
degrees on either side of the celestial equator, during 
the long Uranian year. Already, in considering the 
seasons of Venus, I have dealt with a peculiarity of 
this sort ; but in the case of Uranus the effects are more 
serious. We have only to consider what would be the 
result of so wide a range of solar excursion north and 
south of the celestial equator in a latitude correspond- 
ing to that of London, to see how importantly the 
climatic relations of a planet like Uranus, occupying 
eighty-four years in circling once round the sun, must 
be affected by such a peculiarity. TTe know that in 
the latitude of London the sun reaches at noon, in 
spring or autumn, an elevation of about 3S|- degrees 
above the southern horizon, that in summer he passes 
the meridian 23J degrees higher, while in winter he 
passes the meridian 23^- degrees lower, or only fifteen 
degrees above the horizon. But in a similar Uranian 
latitude, while the sun would reach the same meridian 
elevation in spring or autumn, he would in summer 
travel throuo-hout the dav in a small circle, fourteen 
degrees only from the pole (raised of course 51 J de- 
crees above the northern horizon. And obviouslv, 



180 OTHER WORLDS THAN OURS. 

since the year of the "[Iranians lasts eighty-four of out 
years, the continuance of the sun above the horizon 
would last for many years.* So far there is nothing 
to render life in Uranus unpleasant, always supposing 
the small amount of light and heat supplied by the 
sun to be compensated by some such atmospheric ar- 
rangements as physicists have thought necessary for 
the convenience of the more distant planets. Bui;, 
w T hen we consider the nature of the Uranian winter, 
we find the circumstances such as no such arrangements 
can be conceived to alleviate. The winter path of 
the Uranian sun, in a latitude corresponding to that 
of London, is just as fully pressed below the horizon as 
the summer path is raised above it. At midnight the 
sun is 65 J- degrees, at nominal noon he is 37^ degrees 
below the southern horizon. And as with the summer 
day, so with the winter night, years elapse before 
either comes to an end. For npward of twenty years, 
in a latitude corresponding to that of London, the 
Uranians — if there are any — never see the small Ura- 
nian sun. During all this long time, too, a sight even 
is denied them of all parts of the solar system, interior 
to the orbit of Uranus ; though this deprivation cannot 
be regarded as very serious when it is remembered 
that to such eyesight as ours Saturn could barely be 

* Exact calculation applied to relations so uncertain as those here in 
question would be out of place. From a careful construction, however, 
with 76° as the assumed value of the inclination of the equator of 
Uranus to the plane of his orbit, I find that the sun would continue 
above his horizon in summer for about 2Sj years. Of course, it follows 
that the sun would continue below the horizon for an equally long 
period m winter ! 



URANUS AND NEPTUNE— ARCTIC PLANETS. 181 

visible from Uranus, even when most favorably situ- 
ated,* while Jupiter, always near the sun, could only 
be occasionally seen, shining with a light somewhat 
less than a fiftieth of that which he reflects to us when 
in opposition. 

When we consider other latitudes, we still find 
Uranus ill provided for as respects his winter season. 
In all latitudes nearer the pole than the latitude just 
considered, the Uranians have winters lasting from 
twenty years to upward of forty. In latitudes nearer 
the equator the winter night is shorter, but we must 
approach quite close to the equator before we reach a 
latitude where the winter night lasts less than a year 
or so. Over a belt extending about fourteen degrees 
on each side of the equator there is a perennial suc- 
cession of days and nights never exceeding the full 
duration of the Uranian diumal rotation. But we 
must not suppose that we have thus found an Elysian 
zone in Uranus. The immense range of the sun's 
excursions produces here also a variety of seasonal 
changes which we should find altogether unendurable. 
From a sun barely rising above the horizon in winter, 
to a sun which rises vertically overhead twice in the 
course of the Uranian summer, is a change which 



* Admiral Smyth speaks of Saturn as a fine morning and evening 
star for the Uranians ; but, though Saturn may be visible, he can hardly 
be a fine object. At his elongations he is twice as far from the Urani- 
ans as he is from us when in opposition, and further he presents but a 
half disk. His light must in fact be reduced to less than one-eighth of 
that which he presents to us when in opposition; and, as, instead of 
being on a black sky, he must be always seen from Urauus on a twilight 
sky, he cannot appear a very fine object. 



1 82 OTHER WORLDS THAN OURS. 

hardly accords with our views of what is desirable in 
the progress of the seasons. At the equator itself 
there are in reality two summers, occurring at the 
period of the sun's passing the celestial equator. 
Here for many years together the sun passes day after 
day to a point nearly overhead. But then comes the 
long winter, in the heart of which the sun rises barely 
fourteen degrees above the northern or southern hori- 
zon. By whatever arrangement we render the long 
Uranian winters in this part of the planet endurable, 
we render the heat of his long summers unendurable ; 
and vice versa, if we conceive of atmospheric relations 
which would render his summers pleasing, we have 
caused his winters to be so intensely cold that no 
creatures we are familiar with could endure the pro- 
longed and bitter frosts, contrasting so distressingly 
with the imagined geniality of his summer weather. 

If Uranus be inhabited at all, then, it must be by 
creatures constituted in a very different manner from 
any with which we are acquainted. To such crea- 
tures, if any among them be gifted with intelligence, 
the heavens, though not adorned with planets, must 
yet present an interesting subject of study. The posi- 
tion of the pole, lying close by the zodiac, so that 
among the zodiacal constellations there must be all 
the varieties of motion which we recognize in passing 
from the equatorial to polar constellations, would lead 
to a certain complexity in celestial charts and globes, 
which would invite us to the conclusion that the 
[Iranians must be capital mathematicians. Then 
there are certain astronomical subjects of study to 



VPAXUS AXD NEPTUNE— ARCTIC PLANETS. 183 

which their mathematical powers may be devoted per- 
haps more successfully than those of our astronomers. 
For example, the wide sweep of the planet's orbit 
would enable the Uranians to recognize a displace- 
ment of the stars in the course of the long Uranian 
year. The star Alpha Centauri, which only exhibits 
to the terrestrial observer an annual parallax of one 
second, would exhibit to the observer in Uranus a dis- 
placement of about the third part of a minute. Other 
stars would be affected in like proportion, and per- 
haps the Uranians may thus be enabled to form some 
conception of that relation which hitherto has proved 
too baffling a problem to our astronomers — the actual 
configuration of the nearer parts of the sidereal sys- 
tem. The ISleptunians would of course be even more 
favorably circumstanced. 

One difficulty presents itself, however, in thus con- 
sidering the prospects of the Uranian and ISTeptunian 
astronomers. The enormous length of the year of 
each planet requires that either the astronomers in 
Uranus and J^eptune should be very long-lived, or 
that they should be very enthusiastic in the cause of 
science, to prosecute singly such observations as Hen- 
derson, Olbers, or Peters, have singly prosecuted on 
our earth. A Uranian who made one set of obser- 
vations to determine stellar parallax when he was, 
Bay, twenty-five years old, would have to wait till he 
had nearly reached the threescore years and ten (not 
perhaps allotted as the span of Uranian life) before he 
could make the corresponding set, by comparing which 
with the former stellar parallax was to be determined. 



184 OTHER WORLDS THAN OURS. 

In Neptune life must be prolonged over the century 
(unless the study of observational astronomy com- 
mence during the babyhood of the Neptunians) in 
order that a complete set of observations for determin 
ing stellar parallax should be carried out. One cannot 
but conceive that a certain sluggishness must mark the 
progress of astronomy in these far-off worlds under 
such circumstances. In fact, the mere consideration 
that, after a constellation has passed away from the 
nocturnal skies of Uranus or Neptune, thirty or forty 
years in one case, and seventy or eighty in the other, 
must pass before the constellation again becomes fa- 
vorably visible, suggests characteristics of astronomi- 
cal observation altogether different from those we are 
familiar with. 

Admiral Smyth suggests that these distant planets 
must be convenient outposts for watching the ap- 
proach or recession of comets ; but, with all diffidence, 
I would venture to point out that the inhabitants of 
the earth are, on the whole, more favorably situated in 
this respect. Every large comet which approaches 
tolerably near to the sun during perihelion passage is 
as likely to be seen as to be missed by the inhabitants 
of earth; but scarcely one out of a thousand such 
comets would be seen from Uranus or Neptune, since, 
to be visible, a comet must approach the sun or recede 
from him along a course passing tolerably near to the 
particular position of either planet at the time ; and 
the chances in the case of any individual comet would 
be enormously against such a contingency. 

"With eyesight such as ours the Uranians could 



URANUS AND NEPTUNE— ARCTIC PLANETS. 185 

distinctly see Neptune when in opposition, but the 
Neptunians would be wholly unable to see Uranus, or 
indeed any known planet of the solar system. 

Perhaps, though we have very little evidence on 
the point, it will be thought more reasonable to sup- 
pose that Uranus and Neptune are suns to their re- 
spective systems of satellites, than to imagine that 
these two drearily-circumstanced planets are them- 
selves inhabited. Their satellites cannot possibly 
compensate, to any noteworthy extent, for the small 
amount of solar light or heat which reaches their 
primaries. On the other hand, it is not difficult to 
conceive that the planets may afford an important 
supply of heat (at any rate) to their dependent orbs. 
Certainly, so far as the evidence we have extends, 
Uranus and Neptune resemble Saturn and Jupiter too 
closely not to warrant the application of any argu- 
ments deduced from the appearance of the two giant 
planets to the case of their inferior but still gigantic 
brethren. 

Viewing the matter thus, we seem led to the con- 
clusion that the planets which lie outside the zone of 
asteroids are distinguished from those within that belt, 
not merely, as had so long been recognized, in the 
attributes of size, density, rapidity of rotation, and 
complexity of the systems circling round them, but in 
this more important and more interesting circum- 
stance, that they and their dependent orbs are real 
miniatures of the solar system. Four suns they would 
seem to be, not indeed suns resplendent like the pri- 
mary sun round which they travel, but still giving out 



lS6 OTHER WORLDS THAN OURS. 

perhaps no insignificant supply of light ; not heated 
to incandescence as he is, but still supplying an 
amount of heat proportionately far greater than the 
quantity of light they give forth : in fine, not, as he is 
to the inner planets, the sole source whence all sup- 
plies of force are derived, but adding their influence 
to his in a variety of complicated but doubtless well- 
ordered combinations, in such sort that the small 
worlds which circle around them are provided with all 
that is needful to the well-being of their inhabitants. 



CHAPTEE VIII. 

THE MOON AND OTHER SATELLITES. 

Although I do not think that the moon can be re- 
garded as probably at present the abode of life, there 
are many reasons for studying in a work on other 
worlds the various relations she presents to us. In 
the first place, she subserves various useful purposes 
in the economy of our own earth ; then there are cir- 
cumstances in her appearance which suggest that at 
one time there may have been life upon her surface ; 
and, lastly, she affords us the only information we 
have concerning the probable relations presented by 
the noble systems of moons which circle around Jupi- 
ter and the other planets outside the orbit of the 
asteroids. 

Now, with regard to the present habitability of the 
moon, it may be remarked that we are not justified in 
asserting positively that no life exists upon her sur- 
face. Life has been found under conditions so strange 
— we have been so often mistaken in assuming that 
here certainly, or there, no living creatures can possi- 
bly exist — that it would bo rash indeed to dogmatize 
respecting the state of the moon in this respect. 



1 88 OTHER WORLDS THAN OURS. 

Still, in the case of the moon we have relations 
wholly different in character from those we have 
hitherto had to consider. We no longer have to deal 
with a question of the various degrees of heat and 
cold, of atmospheric rarity or density, and the like, 
but with relations which do not in the slightest degree 
resemble those we are familiar with on earth. 

In the first place, the moon has no appreciable 
atmosphere. We have long known this quite certain- 
ly, because we see that when stars are occulted by the 
moon they disappear instantaneously, whereas we 
know this would not be the case had the moon an at- 
mosphere of appreciable extent. But if any doubt 
could have remained, the evidence of the spectroscope 
in Mr. Huggins's hands would have sufficed to remove 
it. He has never been able to detect a sign of the 
existence of any lunar atmosphere, though Mars and 
Jupiter, so much farther from us, have afforded dis- 
tinct evidence respecting the atmospheres which sur- 
round their surface. 

Then, secondly, there are no seas or oceans on the 
moon. Were there any large tracts of water, the 
tremendous heat to which the moon is subjected dur- 
ing the course of the long lunar day (lasting a fort- 
night of our time) would certainly cause enormous 
quantities of water to evaporate; and not only would 
the effects of this process be distinctly recognizable 
by our telescopists, but the spectroscope would exhibit 
in an unmistakable manner the presence of the aque- 
ous vapor thus formed. 

Thirdly, there are no lunar seasons. The inclina- 



THE MOON AND OTHER SATELLITES. 189 

tion of the moon's axis to the orbit in which she 
travels round the sun is nearly 89°, and with this in- 
clination there can be no appreciable seasonal 
changes. 

Fourthly, the enormous length of the lunar day is 
altogether opposed to our conceptions of what is suit- 
able for animal or vegetable life. The lunar day lasts 
about a fortnight, and the lunar night is, of course, 
equally long. Were this all, the inconvenience of the 
arrangement would be unbearable by beings like our- 
selves. But far more serious consequences must result 
from the combination of the arrangement witli the 
want of an atmosphere ; for whereas during the lunar 
day the surface of the moon is exposed to an incon- 
ceivably intense direct heat, undoubtedly sufficient to 
heat that surface far above the boiling point, during 
the lunar night the heat is radiated rapidly away into 
space (no atmosphere checking the process), and an 
intensity of cold must prevail of which we can form 
but imperfect conceptions." 

The mere fact that our earth is always invisible 

* The moon's physical habitudes are in fact so very different from 
those of the earth that one cannot read without astonishment the well- 
known passage in which Sir W. Herschel pleads for the moon's habita- 
bility. " Its situation, with respect to the sun," he says, " is much like 
that of the earth, and by a rotation on its axis it enjoys an agreeable 
variety of seasons (!) and of day and night. To the moon, our globe 
will appear to be a very capital satellite, undergoing the same regular 
changes of illumination as the moon does to the earth. The sun, the 
planets, and the starry constellations of the heavens, will rise and set 
there as they do here, and heavy bodies will fall on the moon as they 
do on the earth. T/iere seems only to be wanting, in order to complete the 
analogy, that it should be inhabited like the earth." The evidence is, how- 
ever, all the other way. 



i 9 o OTHER WORLDS THAN OURS. 

to three-sevenths of the moon's surface is one which 
points very strongly to the conclusion that the present 
condition of the moon is not the one best calculated 
to meet the wants of living creatures on her surface. 
In long-past ages, when her rotation had not yet been 
forced into accordance with her revolution * (as at 
present), the earth must have subserved a variety of 
most important purposes. If water then existed on 
the surface of the moon, the earth must have raised 
tidal waves in her oceans. She must further have 
reflected enormous supplies of light and heat toward 
her dependent orb, even if at that time she were not 
a secondary sun for the lunarians. She must have 
travelled across the lunar skies as the moon travels 
over ours, presenting a variety of interesting and beau- 
tiful phases affording useful time-measures, and so 
enabling the travellers on the moon in those long-past 
ages to guide their course in safety over her oceans or 
her deserts. But now she is invisible from a large 
portion of the moon's surface, and almost a fixture in 

* The researches of Adams into the peculiarity of the moon's motion, 
called her acceleration, suffice to show that, under the influence of the 
moon's attraction on our oceans, the earth's rotation is gradually dimin- 
ishing ; so that, though many millions of ages must elapse first, she will 
one day so rotate as to keep always the same face turned toward her 
satellite. We cannot doubt that it has been by a process of this sort 
that the moon's rotation has been brought to its present rate. In fact, 
independently of the evidence afforded by the earth's gradual loss ui 
rotation, we cannot account for the moon's peculiarity of rotation with 
out regarding it as due to the earth's controlling influence. A perfectly 
homogeneous sphere, started on a direct line at the moon's distance, and 
with the same velocity, would travel without rotation on an orbit like 
the moon's, and would thus in completing a revolution exhibit everj 
part of its surface to us. 



THE MOON AND OTHER SATELLITES. 191 

the skies of those parts, even, of the moon whence she 
can be seen. "Were there lnnar oceans, she could raise 
no tides in them. Were there a lunar atmosphere, 
she could shed no heat, to be garnered up, so to speak, 
by that atmosphere, and to compensate, in some sort, 
for the long abseuce of the sun. 

But have we evidence that at some far-distant 
epoch the moon was inhabited ? Taking for our guid- 
ance the analogies which are available to us, can we 
really conclude that once, in all probability, those bar- 
ren wastes were clothed with vegetation, those dreary 
solitudes the abode of life ? 

When we contemplate with attention the lunar 
surface, considering the indications it presents of past 
activities, we are led to inquire how the forces which 
have been so busily at work were expended. If Na- 
ture, studied thoughtfully, teaches us the lesson that 
there is no form of force which is not the representa- 
tive of some other preacting form of force, she also 
teaches us that no form of force ever works without 
generating other forces as its own energies are expend- 
ed. The meteor which sweeps with planetary velo- 
city through space may be brought to rest upon the 
sun, but the energy stored up in its motions is not 
wasted ; the sun may expend the stores of force he 
derives from meteoric impact, but not idly;* all 

* The question may be asked, What becomes of the immense sup- 
plies of light and heat continually poured by the sun and other stars 
into space ? We cannot tell ; yet we know certainly that they cannot 
be wasted. The heat of Arcturus, measured by Mr. Stone, gives an ac 
count of one large portion of the stellar heat-supplies, because we know 
that, small as the amount we receive may be, we must multiply thai 



1 9 2 OTHER WORLDS THAN OURS. 

round us we see the fruits of solar energies, we feel 
them within ourselves, we exert them upon others. 
And, therefore, when we see on the moon signs that 
her surface was at one time upheaved by tremendous 
volcanic forces, we are led to the conclusion that be- 
tween the era when she was thus disturbed, and the 
present time, when she seems absolutely quiescent, 
there must have been a period when her energies were 
employed in sustaining various forms of life. There 
has, in this instance, been a process resembling ex- 
haustion, though we know the forms of force which 
have passed away from the moon have not really 
ceased to exist ; but before the lunar forces were dis- 
sipated into space, so to speak, they must have sub- 
served that great purpose which seems the end of all 
Nature's workings — the support of life. 

Associated, however, with this subject, there are 
questions of a perplexing character, which invite our 
careful consideration. If life ever existed on the 
moon, that orb must have possessed an atmosphere 

amount millions on millions of times to get the total received by all the 
orbs in space from this particular sun. But we know that a large por- 
tion of our sun's light and heat must either fail to fall on any other orbs, 
or must be gradually exhausted in its progress through space (for, if 
lines from the sun in every direction encountered orbs, the sky ought to 
be lighted up at all times with star-splendor — which is no other than 
sun-splendor). In either case we cannot tell what becomes of the por- 
tion seemingly wasted, though in the latter case we may affirm confi- 
dently that there is simply a change in the nature of the force. In both 
cases we know that the total of force in the universe remains undimin- 
ished. There is, indeed, a seeming contradiction here ; but it is not dif- 
ferent in character from the seeming contradictions suggested by the 
consideration of infinite space and infinite time, which yet we are com* 
pelled to recognize as absolutely as finite space or finite time. 



THE MOON AND OTHER SATELLITES. ^3 

and seas. Independently, also, of our views on the 
subject of life upon the moon, we are led, by the reve- 
lations of the spectroscope respecting the solar system, 
to believe that all the bodies within that system are in 
a general sense similarly constituted ; and, if this be 
so, there must once have been oceans and air upon the 
moon. What has become of the moon's atmospheric 
envelope, and of the lunar oceans ? 

In four several ways this question has been an- 
swered. Some have thought that the oceans and air 
have been withdrawn into cavities within the moon's 
substance. Others have imagined that the air and 
oceans may have passed away to the farther hemi- 
sphere of the moon. According to a third theory, a 
comet has carried off the lunar oceans and atmosphere. 
And, lastly, a fourth theory has been maintained, ac- 
cording to which the lunar air, and a fortiori the 
lunar seas, have been changed by intensity of cold into 
the solid form. 

Of these theories, the first and last only seem 
worthy of consideration. We see so much of the 
moon's farther hemisphere during her librations that 
we must perforce reject the second, even if we had 
any trustworthy analogy for believing so strange an 
arrangement to be possible.* The third theory is op- 

* Prof. Newcombe, of America, has shown excellent reasons for 
doubting whether even that displacement of the moon's gravity, on 
"shich the theory has been based, can be admitted as an established 
fact. Independently of this, however, the theory will not bear exami- 
nation. Any one who will draw a cross-section of the moon (in a plane 
passing through the earth), and endeavor to assign such a position to 
an atmosphere of moderate extent that, even during the moon's extreme 
13 



i 9 4 



OTHER WORLDS THAN OURS. 



posed by all that modern astronomy teaches respect- 
ing the constitution of comets. 

The theory that an atmosphere formerly surround- 
ing the moon has passed with the lunar oceans into 
the interior of our satellite has been supported by 
physicists of considerable eminence. The relatively 
low specific gravity of the moon (little more than half 
the earth's) suggests the possibility that cavities large 
enough to contain even all the waters of our own 
oceans may exist within the moon. Nor does the fact 
that we can see no unmistakable signs of chasms ex- 
tending deep into the moon's substance suffice to ren- 
der the theory untenable, or even improbable. It is 
difficult to understand how the inrush of the waters 
took place. Certainly it cannot have happened while 
ine moon's volcanic forces were in vigorous action; 
yet a period must undoubtedly have arrived when by 
little and little the waters could retire within the 
moon's substance without being vaporized. From 
what we know of volcanic action on the earth, the 
lunar volcanoes must have drawn fresh supplies of 
energy from the gradual influx of water ; and one can 
thus understand why the aspect of the moon indicates 
that, up to the last moment, so to speak, of her exist- 
ence as a world, the forces upheaving her crust were 
busily at work. We can thus see how it has come to 
pass that the moon's surface shows so few signs of the 
action of rain or running water. 

The theory that the lunar oceans have become 

librations, no signs of the atmosphere could be perceptible from ih? 
fcarth, will at once see that the theory is untenable. 



THE MOON AND OTHER SATELLITES. 



*95 



frozen, and that afterward even the gases forming the 
lunar atmosphere have become solidified, was main- 
tained by Buffon and Bailly in the last century, and 
has been supported by several astronomers in our own 
day. In some respects, the aspect of the moon 
(especially the absence of well-marked colors from 
her surface) seems to favor the theory. Nor need 
the excessive heat to which the moon's surface is 
exposed for weeks at a time be considered a sufficient 
reason for rejecting it, because we have no means of 
judging how that heat would act where there is no 
atmosphere to prevent its immediate and entire reflec- 
tion into space. "We know that, despite the intense 
heat which is poured upon the summits of the Hima- 
layas, the snow there — though a portion may melt 
during the day — remains year after year and age after 
age undiminished ; and on the summit of the Hima- 
layas the atmosphere is dense and heavy compared with 
that which exists even in the lowest abysms of the lunar 
ravines. If absolute reliance be placed on the results 
which have been deduced from the application of the 
great Parsonstown mirror to the measurement of the 
lunar heat, it would seem as though we must abandon 
the belief in the existence of frozen oxygen or nitrogen 
on the moon's surface, since, according to those re- 
sults, a large proportion of the moon's heat is radiant 
— in other words, the moon's surface has been actually 
raised to a high degree of heat by the solar rays. At 
present, however, physicists are not prepared to look 
with perfect confidence on the method by which, in the 
researches made at Parsonstown, an attempt has been 



L 9 6 OTHER WORLDS THAN OURS. 

made to distinguish between the heat which the moon 
reflects and that which she radiates into space. 

On the whole, however, the former theory seems to 
have the strongest evidence in its favor, or rather the 
least decisive evidence against it. 

In considering the systems of bodies which circle 
around the outer planets, we are struck at once by 
several marked circumstances of contrast between their 
condition and that of our own moon. 

In the first place, we have no satisfactory evidence 
that the satellites of Jupiter and Saturn turn always 
the same face toward their primary. It is true that 
Sir William Herschel was led by certain observations 
of the satellites of Jupiter to conclude that this relation 
holds in their case. But we have far stronger evidence 
against such a view, in the fact that modern observers, 
armed with telescopes of the most exquisite defining 
powers, have not only been unable to confirm the rela- 
tively rough observations made by Herschel, but have 
noticed peculiarities of appearance only explicable by 
the theory that the rotation of the satellites is quite in- 
dependent of their motion of revolution around Jupiter. 
Dawes, for instance, has observed that the markings 
seen on the third satellite, when transiting Jupiter's 
disk, are variable. Bond has seen this satellite as a 
well-defined black spot on certain occasions, while on 
others it has appeared quite bright on the disk of the 
planet. He once saw this satellite bright as it entered 
on the disk of Jupiter, and about half an hour later as 
a dark spot ; while Mr. Prince, with a powerful re- 
flector, has seen the satellite dark first and afterward 



THE MOON AND OTHER SATELLITES. 



97 



bright. It need hardly be said that, if the satellite 
turned always the same face toward its primary, no 
such varieties of appearance would be presented dur- 
ing transit. The following passage from Webb's " Ce- 
lestial Objects " points strongly also to the conclusion 
that the rotation of the Jovial satellites must be inde- 
pendent of their revolution. After mentioning that 
the variable light of the satellites may be caused by 
the existence of spots upon their surface, he proceeds : 
" A stranger source of anomaly has been perceived— 
the disks themselves do not always appear of the same 
size or form. Maraldi noticed the former fact in 1707, 
Iierschel ninety years afterward inferring also the 
latter, and both have since been confirmed. Beer and 
Miidler, Lassell and Secchi, have sometimes seen the 
disk of the second satellite larger than that of the first ; 
and. Lassell, and Secchi and his assistant, have dis- 
tinctly seen that of the third satellite irregular and 
elliptical ; while, according to the Roman observers, 
the ellipse does not always lie the same way." 

It will easily be seen that these peculiarities indi- 
cate the existence of dark markings on these bodies, 
and that, as the satellites rotate, the varying position 
of these markings causes the satellites seeminodv to 
change in figure, since the brighter part of the satellite 
would be that which would determine its apparent 
figure. And further, since the change of figure shows 
no correspondence with the position of the satellites 
in their revolution, we infer that their revolution is 
independent of their rotation. 

It is worthy of notice, however, that even if the 



i 9 8 OTHER WORLDS THAN OURS. 

inner satellites turned always the same face toward 
their primary, the peculiarity would not (as in the case 
of our moon) result in an inordinate lengthening of 
their diurnal period, since Jupiter's two inner satellites 
complete a revolution in one day eighteen and a half 
hours, and three days thirteen hours respectively ; 
while the revolutions of Saturn's five inner satellites 
are severally accomplished in twenty-two and a half 
hours, one day nine hours, one day twenty-one hours, 
two days eighteen hours, and four days twelve and a 
half hours. 

So far as we can judge from Laplace's estimates, 
the specific gravity of Jupiter's moons must be very 
small indeed, ranging from one-ninth to four-fifths of 
the specific gravity of water. But very little reliance 
can be placed on these results, because the only evidence 
we have respecting the mass of the satellites is that 
founded on the perturbations to which their motions 
are subjected, and it is very difficult indeed to estimate 
these perturbations. "When to this we add the cir- 
cumstance that little reliance can be placed on meas- 
urements of the minute disks presented by the satel- 
lites, it will be seen that our estimate of the specific 
gravities of these bodies cannot by any means be 
regarded as trustworthy. 

As seen from his satellites, Jupiter must present a 
magnificent scene. To the inhabitants, if such there 
be, of the innermost satellite, he exhibits a disk nearly 
twenty degrees in diameter. Thus, whereas there 
might be about seven hundred moons such as ours 
placed all round our horizon, the disk of Jupiter, as 



THE MOON AND OTHER SATELLITES. lg9 

seen from the inner satellite, could occupy a full 
eighteenth part of the horizon's circumference. The 
disk of Jupiter, as so seen, would cover a space on the 
heavens exceeding more than fourteen hundred times 
that which our moon covers. To the second satellite, 
Jupiter presents a disk about 12|- degrees in diameter, 
or about six hundred times as large as our moon's. 
To the third satellite he shows a disk about 7f degrees 
in diameter, or more than two hundred times the size 
of the moon's. And, lastly, the inhabitants even of 
the farthermost satellite see him with a diameter of 
about 4^ degrees — that is, with a disk more than sixty- 
five times as large as that of our moon. So that, if 
the views I have put forward respecting Jupiter be 
correct, the enormous space he covers on the skies of 
his respective satellites must suffice to compensate in 
part for the relatively small amount of heat which he 
can be supposed capable of emitting. 

If the satellites rotate with a motion independent 
of their revolution, Jupiter passes across their skies 
like a vast moon, exhibiting phases such as those pre- 
sented by ours, but on a far vaster scale. But, besides 
his phases, he must exhibit to the inhabitants of his 
satellites the most marvellous picture that can be con- 
ceived. His belts' changes of figure and color, only 
rendered visible to our astronomers by powerful tele- 
scopic aid, must be distinctly visible to creatures on 
his satellites, and cannot but afford reasoning beings 
on those orbs a most astounding theme for study and 
admiration. 

To the inhabitants of the satellites which circle 



zoo OTHER WORLDS THAN OURS. 

round Saturn, the ringed planet must present an even 
more interesting spectacle. His disk, as seen from the 
nearest of his satellites, has a diameter of IT degrees, 
and an apparent surface exceeding more than nine 
hundred times that of the moon. From the farthest 
satellite his disk is less than a degree in diameter, and 
therefore not quite four times as large as our moon's. 
Between these limits the apparent size of Saturn va- 
ries as we pass from satellite to satellite ; but from the 
sixth satellite his apparent surface is twenty-five 
times, while from the seventh it is sixteen times as 
large as the moon's ; so that the outer satellite is quite 
exceptionally circumstanced in this respect. 

It is not so much from the apparent size of his 
disk, however (though in the case of all the inner 
satellites that must be a most remarkable relation), as 
from the peculiar character of his ring-system, that 
Saturn must derive his chief interest. It is true that 
the inner satellites travel nearly in the plane of the 
rings, so as always to see them nearly edgewise. But, 
even so viewed, the rings must present a most striking 
appearance. From the inner satellite, indeed, the ex- 
treme span of the ring-system must be more than 90 
degrees ; * so that when one extremity is seen on the 
horizon the system would appear as an arch thickest 
in the middle, extending over an arc of about 93 de- 
grees, and having the disk of Saturn at its centre. 
When tlhe whole of this arch is illuminated, Saturn is 
"full;" at other times he presents all the phases 

* About 93° according to the best estimates of the dimensions of 
the rings and the distance of the satellite. 



THE MOON AND OTHER SATELLITES. 201 

shown by our moon, and the arch of light is corre- 
spondingly shortened. Saturn " full " and in the ze- 
nith, with the ring-system dependent on either side of 
bis disk, must be a glorious spectacle as seen from cer- 
tain regions of his innermost satellite. The display 
would diminish in grandeur, though not perhaps in 
interest, as seen from satellites farther and farther 
away. But the inhabitants of the outermost satellite 
of all have the privilege of seeing the Saturnian ring- 
system opened out much more fully than as seen from 
the other satellites, since the path of this moon is in- 
clined some 15 degrees to the plane of the ring. 

Of the satellites of Uranus and JSTeptune little can 
be said, because so little is known either respecting 
these orbs themselves or their primaries. I may re- 
mark that, despite the evidence brought forward to 
the contrary, I have very little doubt that Uranus has 
at least eight satellites. Four of those discovered by 
Sir W. Herschel have not indeed been yet identified ; 
but one cannot read the account of his method of pro- 
cedure without feeling that no amount of mere ne«:a- 
tive evidence can be opposed effectively to the posi- 
tive information he has left respecting these four orbs. 
Indeed, when we remember that Uranus is twice as 
far from us as Saturn, while it has only been in recent 
times that the eighth Saturnian satellite (the seventh 
in position) has been discovered, we cannot but con- 
sider that in all probability many more Uranian satel- 
lites will one day be discovered. Neptune also, no 
doubt, has a large family of satellites circling around 
him. 



CHAPTEE IX. 

meteo.es and comets : THEIK office in the solas 

SYSTEM. 

The^e are few more interesting chapters in the 
history of astronomy than that which deals with the 
gradual introduction of meteors into an important 
position in the economy of the solar system. Regarded 
for a long time as simply atmospheric phenomena 
(though many ancient philosophers held another opin- 
ion), it has only been after a long and persistent se- 
ries of researches that they have come at length to be 
regarded in their true light. But, though the history 
of those researches is not only full of interest, but 
highly instructive and encouraging, this is not the 
place for entering at length into its details. I must 
present facts and conclusions, rather than the narra- 
tive of observations or calculations by which those 
facts and conclusions have been established. Nay, it 
would seem at first sight as though even the nature 
of meteors could have very little to do with the subject 
of this treatise, since we cannot suppose these small 
bodies to be inhabited worlds. It will be found, how- 
ever, that, though this is certainly truo. there are 



METEORS AND COMETS. 203 

reasons for believing that meteors are associated in a 
very intimate manner with the general relations of 
the scheme of worlds forming the solar system. 

Under the head " Meteors " I include all those ob- 
jects which reach the earth's atmosphere from with- 
out, whether they actually make their way to her sur- 
face unbroken, like the aerolites ; or explode into 
small fragments, as bolides and fire balls have been ob- 
served to do ; or are apparently consumed in travers- 
ing the upper regions of the air, as happens with shoot- 
ing or falling stars. All these objects, we now know, 
represent in reality bodies of greater or less size, 
which, before their encounter with the earth, were trav- 
elling around the sun in orbits of greater or less eccen- 
tricity. The larger masses, though they must be very 
numerous (or our earth would not once in many ages 
encounter any of them), are yet relatively few in 
number as compared with fire-balls, and still more so 
in comparison with shooting- stars. It has been calcu- 
lated, indeed, that these last are so numerous that the 
earth, in passing through a region of space equal to 
her own dimensions, must encounter no less than 
thirteen thousand of them ; while of yet smaller bod- 
ies, whose passage through, our air would only be rec- 
ognizable by telescopic aid, she is supposed to en- 
counter as many as forty thousand within a similar 
space. Without laying great stress on these calcula- 
tions, we may yet feel quite sure that the earth must 
encounter enormous numbers of these bodies, from 
the mere fact that, though at any fixed station but a 
minute slice (so to speak) of the earth's atmosphere is 



20 4 OTHER WORLDS THAN OURS. 

within view, and even but a portion only of that slice 
visible to a single observer, six or seven falling stars on 
the average may be seen during each hour of the night, 

It will be seen, then, that a problem of the utmost 
importance was involved in the question whether these 
bodies came from the interplanetary spaces, or from 
the region of space over which the earth's own attrac- 
tive energies prevail. Now that we know the former 
view to be the true one, we recognize the fact that, 
though each meteor may be individually insignificant, 
the meteors of the solar system, looked on as a single 
family, form a highly-interesting and important portion 
of the solar system. 

But now a yet more significant relation has to be 
considered. Regarding meteors as planetary bodies, 
they might yet be relatively unimportant, if we had 
any reason to believe that they form a sort of zone or 
belt near the earth's orbit, reseufbling in a sense the 
asteroidal zone, only composed of far smaller constitu- 
ent bodies. We could not then argue, from the number 
of meteors encountered in a given time by the earth, 
the largeness of the total number of these bodies ; for it 
might well be that this zone had no counterpart, either 
in the outer part of the planetary system or within 
the orbit of the earth. What has actually been dis- 
covered, however, respecting the paths along which the 
meteoric bodies have reached the earth, immensely en- 
hances the importance of these objects. 

It has been proved, on evidence perfectly incontes- 
table, that two well-marked meteoric systems travel in 
orbits of enormous eccentricity. The August meteors 



METEORS AXD COMETS. 



205 



travel on a path so eccentric that in the neighborhood 
of the earth's orbit it may be regarded as almost para- 
bolic in figure. That it is not absolutely parabolic is 
shown, of course, by the fact that a period has been 
assigned to the revolution of the members of the zone. 
jSTo observations have been indeed made by which as- 
tronomers could determine the orbit of these meteors, 
since for this purpose an exact determination of the 
velocity with which they enter the earth's atmosphere 
would be requisite, while the observations actually 
made to determine their velocity are confessedly in- 
exact. But an association, altogether too close to be 
regarded as accidental, has been discovered between 
their orbit and that of a bright comet which appeared 
in 1862, and this, combined with what has since been 
established respecting the relations between comets and 
meteors, enables astronomers to adopt quite confident- 
ly the orbit of the comet as that of the meteoric system. 
Now, a period of one hundred and forty -five years im- 
plies, according to Kepler's law, an orbit having a mean 
distance nearly equal to that of Neptune. And since 
the orbit is so eccentric as to brins; these bodies close 
by the earth when they are near perihelion, it follows 
that their aphelion distance must exceed their mean dis- 
tance in the same degree. Hence the aphelion point 
of the August meteors must lie nearly twice as far away 
from us as the orbit of Neptune. 

The November meteors have been shown in like 
manner to travel in a period of thirty-three and a quarter 
years around the sun, the aphelion of their orbit lying 
far beyond the path of Uranus. 



206 OTHER WORLDS THAN OURS. 

So far, then, as we can judge from the only two 
meteoric systems whose orbits can be said to have 
been satisfactorily determined (though there are many 
other systems which have been associated with known 
comets), we are led to the conclusion that the meteoric 
orbits are for the most part eccentric. We know, 
further, that they are inclined in all directions to the 
plane in which the earth travels, because we see that 
their constituent bodies fail upon the earth in direc- 
tions which show no tendency to near coincidence 
with the ecliptic. 

Now, these two circumstances are full of meaning. 
If the meteors travelled in nearly circular orbits, at a 
mean distance nearly equal to the earth's mean dis- 
tance from the sun, then the earth would be certain to 
encounter meteors in the course of her orbital motion 
round the sun. Again, if the meteors travelled in ec- 
centric orbits, whose perihelia lay within the earth's 
orbit, and if these orbits all lay in or near the plane of 
the earth's path, the earth could not fail to encounter 
meteors as she travelled round the sun. But under 
the actual circumstances — the mean distances of the 
meteoric orbits being in no way associated with the 
earth's mean distance, and the inclination of these or- 
bits to the ecliptic not being in any way limited — the 
two questions are at once suggested : 1. What is the 
co priori chance that the earth would encounter the 
members of any meteoric system taken at random? 
and, 2. If this chance be small, what is the conclu- 
sion to be drawn from the fact that the earth encoun- 
ters meteors belonging to many systems ? — the num- 



METEORS AND COMETS. 



207 



ber already recognized being nearly sixty. Now, 
assigning elements at random to a meteor-system, we 
see that, unless the resulting orbit actually coincides 
with the plane of the ecliptic (a relation which would 
not happen in a million trials), the orbit will intersect 
that plane in two points, lying on a straight line 
through the sun. And, for the earth to encounter 
members of the meteoric system, it is requisite that 
one or other of these two points shall he close to the 
earth's orbit. But these points may have any position 
whatever in the plane of the ecliptic, and the chance 
that one of them has the requisite position may be re- 
garded as indefinitely small. It follows, then, that 
the a priori chance of the earth's encountering the 
members of a meteoric system is indefinitely small ; 
and hence we conclude that the number of meteoric 
systems she passes wholly clear of is indefinitely great, 
in comparison with the number whose members she 
encounters. But she actually encounters meteors be- 
longing to no less than fifty-six systems: hence the 
total number of meteoric systems belonging to the 
planetary scheme must be an indefinitely large multi- 
ple of the number fifty-six, or, in other words, it must 
be enormously beyond our powers of conception. 

But this being so, it behooves us to inquire, first of 
all, what extent we must assign to individual meteoric 
systems, and how densely we may suppose meteoric 
masses to be strewn along each system ; and, secondly, 
what may be the nature, quality, and substance of 
these meteoric masses. For we clearly begin to see 
that we are in the presence of relations which may — - 



2 o8 OTHER WORLDS THAN OURS. 

or, I should rather say, which must — affect most im- 
portantly the economy of the solar system. 

Now, we have seen something already of the lon- 
gitudinal extent of meteoric systems, since that extent 
corresponds to the circumference of meteoric orbits, 
and we have seen that these orbits have enormous 
dimensions. We may, indeed, suppose that in some 
cases the whole extent of an orbit is not occupied by 
meteoric masses at any one instant ; but even when, 
as in the case of the November meteors, the annual 
displays wax and wane in splendor, there is no abso- 
lute cessation in the occurrence of star-falls on the 
date corresponding to such a system. And taking full 
account even of the marked diminution which acta- 
ally occurs, we are yet compelled to assign an enor- 
mous longitudinal extent to that portion of the system 
which has been poetically termed " the gem of the 
meteor-ring." For example, in the November meteor- 
system, this portion of the ring cannot be less than 
1,000,000,000 of miles in length. As to the width of a 
meteor-system — that is, its extent in a direction meas- 
ured in the plane of its orbit — we have no satisfactory 
information, because a meteor-system may extend 
enormously on either side of the point through which 
the earth's orbit intersects it, and yet no trace of that 
extension be recognized by observers on the earth. 
Still we may conclude that this dimension lies in ex- 
tent somewhere between the longitudinal extension of 
the system and the depth of the meteor-zone — that is, 
the length of a line taken through its square to the 
plane in which it lies. Now, of this last dimension we 



METEORS AND COMETS. 



209 



can form a tolerably accurate estimate in many in 
stances. We know that so long as meteors belonging 
to any system are flashing into view, our earth is still 
plunging through the system ; and if we know the po- 
sition of the system we can determine its depth in 
this way, just as we could determine the breadth of a 
range of hills if we noticed how long a train, travelling 
with known velocity, took in passing through a tunnel 
which traversed the range of hills in a known direction. 
Judged in this way, the depth of the November meteor- 
zone would seem to be one hundred thousand miles in 
the part traversed by the earth in 1866, about sixty 
thousand miles in the part traversed in 1867, and con- 
siderably greater (though the zone was more sparsely 
strewn with meteors) where the earth crossed the sys- 
tem in 1868 and 1869. 

Now, as regards the density with which meteors 
are strewn in any known system, I must remark on a 
mistake which has been very commonly made. It has 
been thought necessary to consider the velocity with 
which the meteors themselves travel as well as the 
earth's velocity, in order to determine, from the aver- 
age interval of time separating the appearance of 
successive meteors, the average distance separating 
neighboring meteors from each other. This, however, 
is an erroneous mode of dealing with the problem. 
We need only consider the earth's velocity, since the 
meteoric motions cannot possibly tend to increase the 
total number of encounters.* Let us apply this con- 

* Obviously the total number of meteors encountered during the 
earth's passage through a meteor-stream will be the number contained 
14 



210 OTHER WORLDS THAN OURS. 

sideration to enable us to form a rough estimate of 
the number of bodies in the richer part of the Novem- 
ber meteor-system. We may fairly assume that, tak- 
ing the average of the four displays of the years 1866- 
'69, the earth encountered more than one meteor per 
minute as she swept successively through the system ; 
or, conveniently for our purpose, that an average 
distance of 1,000 miles separates meteor from me- 
teor throughout the "gem of the ring." Now, the 
length of the great cluster is at least 1,000,000,000 
miles, its thickness may be fairly assumed as aver- 
aging 100,000 miles, and its width can hardly be less 
than ten times its thickness, since the forces acting 
on the system tend much more largely to affect its 
width than its thickness. Thus, with the assumed 
average of distance (1,000 miles), we find that the 
cluster cannot contain less than (1,000,000 x 100 x 
1,000) or one hundred thousand million members. 

Mr. Alexander Herschel, from observations of the 
amount of light given out by these bodies, and a cal- 
culation founded on the velocity with which they pen- 
etrate our atmosphere, has come to the conclusion 
that they must, for the most part, be very small, rarely, 
perhaps, exceeding a few ounces in weight. We shall 
certainly not exaggerate their weight if we assign one- 
hundredth part of an ounce to each. We thus obtain 
for the weight of the whole cluster one thousand mill- 
in a cylindrical space having a cross-section equal to the earth's, and 
traversing the meteor-stream from side to side. The motion of the 
meteors will affect the particular set of meteors actually found within 
this space as the earth traverses it, but will not affect their number, 
assuming a general uniformity of meteoric distribution. 



METEORS AND COMETS. 



211 



ions of ounces, or about twenty-eight thousand tons. 
The actual weight of the November meteor-system 
cannot, however, but enormously exceed this amount ; 
and therefore we recognize how erroneous that opinion 
is which an eminent astronomer recently expressed, 
who asserted that the united weight of all the bodies 
other than planets in the solar system must be esti- 
mated rather by pounds than by tons. We have cer- 
tainly no reason for thinking that the November sys- 
tem, though one of the most important encountered by 
the earth, is exceptionally important in the solar sys- 
tem. On the contrary, we have every reason the laws 
of probability can afford us, for believing that there 
must be millions of systems equally or more extensive. 
And, further, the fall of enormous masses, many tons 
sometimes in weight, upon the earth, would point to 
the conclusion that the members of the November 
system are exceptionally insignificant as regards their 
individual dimensions. So that we seem forced to the 
conclusion that the aggregate weight of the various 
meteoric systems circulating around the sun must be 
estimated by billions of tons rather than by any of our 
ordinary units. 

I have already referred to the relation which has 
been detected between comets and meteor-systems. Bi- 
zarre as the relation appears, it has been established on 
evidence which cannot reasonably be disputed. It car- 
ries with it results of extreme interest and importance. 

I do not propose here to enter into any considera 
tion of those enormously difficult questions which are 
suggested by the study of cometic phenomena. That 



212 OTHER WORLDS THAN OURS. 

they will before very long receive their solution I 
confidently believe; but in the present state of our 
knowledge it would indeed be hazardous to speculate 
as to what that solution may be. I may remark in 
passing, that, while I recognize in Dr. TyndalPs re- 
cently-promulgated theory on the subject the indica- 
tion of a highly-suggestive and promising line of 
research, I cannot but feel that cometic phenomena 
are far too complicated to be directly accounted for in 
the way pointed out by that distinguished physicist. 
Some of the more obvious, and, I may add, the more 
generally known phenomena, do indeed appear to re- 
ceive a solution when examined under the light of Dr. 
Tyndall's researches, but numbers of others remain 
not only unaccounted for, but standing apparently al- 
together opposed to his theory.* 

But for my present purpose the facts to be princi- 
pally noticed are in a sense independent of any theory 
which may be formed respecting the nature of comets. 
We know that the dimensions of these objects are in 
many cases enormous. We know, further, that there 
must be many thousands of comets remaining undis- 
covered for each that our astronomers have detected. 
And, lastly, we are led to recognize the observed 
association between certain meteor-systems and cer- 
tain comets as indicative of a general law by which, in 
some way as yet unexplained, comets and meteors are 

* The theory recently put forward by Prof. Tait is altogether incon- 
sistent with the history of many comets. Indeed, I have been unable 
to find a single comet whose recorded chauges of appearance counte- 
nance Prof. Tait's views. 



METEORS AND COMETS. 213 

associated together. Thus, independently of the con- 
siderations already adduced, we are led to the conclu- 
sion that meteor-systems must be very numerous; 
while from the fact that a meteor-system so important 
as the November stream is associated with a comet so 
insignificant as Tempel's, we conclude that those mag- 
nificent comets which have blazed in our skies — a 
source at once of wonder and perplexity to the astron- 
omer — must be associated with systems of bodies incal- 
culably more important than the meteor-system which 
has so often filled the heavens with falling; stars. 

Now, combining all these results, we seem fairly 
led to the conclusion that purposes of the utmost im- 
portance in the economy of the solar system must be 
subserved by these uncounted thousands of meteoric 
streams. If, indeed, we could suppose that the planets 
steered clear of them, and that the bodies composing 
them simply circulated unceasingly in their orbits, 
we might form another opinion. But we know that 
meteors are continually falling upon the atmosphere 
of our own earth, either there to be dissipated into 
finest dust or to pass onward, with or without explo- 
sion, to the actual surface of the earth ; and we cannot 
doubt that in a similar way countless thousands of 
meteors are falling, not only upon all the primary 
members of the solar system, but upon asteroids and 
satellites — nay, are even streaming in among the mi- 
nute bodies composing the rings of Saturn. These 
encounters cannot be wholly without result, and it is 
quite conceivable that most injurious consequences 
might ensue to the inhabitants of all the worlds in the 



214 



OTHER WORLDS THAN OURS. 



solar system if the continual supply of meteoric matter 
were importantly diminished. 

Now, if meteoric masses fall continually upon the 
planets, such masses must fall in numbers inconceiv- 
ably greater upon the sun ; and it is here, unless I mis- 
take, that the great purpose of the meteoric systems 
becomes apparent. 

Let us clearly recognize, however, why and how 
the sun must be assaulted by a Continual inrush of 
meteoric bodies. "We have seen how enormous must 
be the number of these bodies ; we know how swiftly 
they travel, and on what eccentric orbits ; but we 
must go farther before we can prove that they fall 
upon the sun. For example, the November meteors 
are enormous in number, and travel with enormous 
velocity in a very eccentric orbit, but they do not ap- 
proach the sun within a distance of nearly ninety mill- 
ions of miles. Nor, indeed, can any known meteoric 
system pour a steady hail of meteors, so to speak, upon 
the sun ; for he is the ruling centre of every meteoric 
system, and therefore under ordinary circumstances 
the meteoric orbits must pass around him, and not in 
such a direction as to intersect his substance. 

But it is to be remembered that meteors must be 
infinitely more crowded in the neighborhood of the 
sun than at a distance from him. An indefinitely 
large number of meteoric orbits must absolutely in- 
tersect in the immediate neighborhood of the sun ; 
and collisions must continually be taking place as 
countless thousands of meteoric flights rush toward 
and past and then away from their perihelia. "Where 



METEORS AND COMETS. 215 

these perihelia lie close to the sun, the velocity with 
which the meteors travel must exceed two hundred 
miles per second, and therefore the collision even of 
two minute meteors must result in the generation of 
an enormous amount of light and heat. But that is 
not all. Among the collisions thus continually taking 
place in the sun's neighborhood there must be a con- 
siderable proportion in which the two bodies are 
brought momentarily almost to rest by the shock. In 
such cases the combined mass of the two meteors 
would fall directly upon the sun, a fresh supply of 
light and heat being generated as they were brought 
again to rest upon his surface. 

Whether in the continual collisions of meteors 
among themselves, and in their precipitation upon the 
sun's surface, we have a sufficient explanation of the 
seemingly exhaustless emission of light and heat from 
the sun, I should not care positively to assert. Prof. 
Thompson, who was one of the first to adopt this 
view, has, I believe, abandoned it ; though it is wor- 
thy of remark that the strongest evidence in its 
favor has been obtained since he withdrew his sup- 
port from it, or at least admitted that the downfall 
of meteors on the sun's surface is not alone sufficient 
to account for the solar light and heat. But I am 
quite certain that there is no flaw in the evidence I 
have adduced from the laws of probability ; and that 
we are bound to accept, as a legitimate conclusion 
from that evidence, the theory that at least an impor- 
tant proportion of the sun's heat is supplied from the 
meteoric streams which circulate in countless millions 



216 OTHER WORLDS THAN OURS. 

around him. I believe that, without adopting any 
unreasonable assumptions, it might readily be shown 
that the whole even of that enormous supply of light 
and heat which the sun emits on every side is derived 
from the meteoric streams belonging to the solar sys- 
tem or drawn in from surrounding space, as the sun, 
attended by his family of planets, sweeps onward amid 
the stellar groups. 

If this view be correct, then the meteor-systems 
constitute, indeed, a most important part of the sun's 
domain. They may be said almost to share with the 
sun a title to be regarded as the source of all the forms 
of force which exist throughout the solar system. It, 
in the energies of living creatures on earth, in the 
forces derived from the fuel that propels our engines, 
or in the power of winds and storms, we trace the 
action of the ruling centre of the solar system, we may 
trace back the chain of causation yet one link farther, 
and see in the sun's emission of light and heat the 
result of forces inherent in the meteoric systems which 
circle around him. 

But we must not forget one most important con- 
sideration, which makes the sun (as might be antici- 
pated) again the chief source of all the forms of force 
existing within his system. The motions of the me- 
teoric masses are almost wholly due to the sun's 
attraction ; and therefore, in so far as those motions 
are to be regarded as a means of renewing the solar 
heat, we must regard the sun's attractive energy as 
the source whence his heat and all the other forms of 
force which he exerts are in reality derived. 



METEORS AND COMETS. 2i y 

Yet one step farther. The sun's attractive energies 
might be increased a thousand-fold, and yet not avail 
to supply the various forms of force which are required 
by his dependent worlds, were there no external ma- 
terial on which those energies could act in such sort 
as to lead to the continual inrush of matter upon the 
solar surface. Nor would it suffice if such materials, 
even in enormous quantities, existed close to the sun. 
It is the distance from which that material is dragged 
toward the sun which gives that orb the power of 
imparting those tremendous velocities to which the 
collisions of the meteoric bodies owe their real effec- 
tiveness. We thus find in distance, in the simple 
element of scale, the true source of the various forms 
of force which are continually exerted throughout the 
solar system. The sun surrounded by millions on 
millions . of meteoric masses close at hand would be 
powerless, but placed as ruler over a space far wider 
than the sphere circled by Neptune's orbit, amid 
which space those countless millions of meteors are 
distributed, he becomes forthwith the centre of a 
thousand forms of force, gathered by him continually 
from the systems of meteors circling around him, and 
distributed by him abundantly and without ceasing to 
his dependent worlds.* 

* Just as this work was about to be placed in the printer's hands 1 
received from Prof. Kirkwood, of America, one of his valuable contri- 
butions to the history of the solar system. In it he points to the 
evidence we have that the sun, as he speeds onward through space, 
passes through regions in which cometic and meteoric materials are now 
richly, now sparsely strewn, and gathers in accordingly new stores of 
force of greater or less amount. The bearing of the views of this acute 
Rud soundly-reasoning astronomer (the Kepler of our day), not only <>d 



2i8 OTHER WORLDS THAN OURS. 

It will not fail to be noticed by the thoughtful 
reader that, adopting this view of the relation in which 
meteoric and cometic systems stand with respect to 
the sun, it seems necessary that we should regard 
those planets which I have endeavored to raise to 
the dignity of secondary suns, as subordinate centres 
of attraction, around which countless thousands of me- 
teoric systems may be supposed to circle. Have we 
any evidence pointing to such a conclusion ? 

Now, there can be no doubt that if Jupiter, the 
nearest of these secondary suns, did so act upon a 
passing comet as to compel that body to circle in 
future around him, instead of pursuing its course 
around the sun, we could not in any way become 
conscious of the event unless the comet were an ex- 
ceptionally large one. I conceive, however, that such 
an event, though undoubtedly possible,* must be so 

the theories dealt with in the above chapter, but on those considered in 
the chapters which follow, will be seen at once. 

* It is necessarily possible in the case of any planet, but must in 
many cases be highly improbable. For example, astronomers sometimes 
assert that meteoric masses passing near the earth might become 
satellites of hers, but in reality this is a very unlikely event, because 
the maximum velocity which a body travelling under the earth's influence 
can have (that is, the velocity acquired by a body travelling from infinity 
to a perigee close to the earth) is less than the velocity with which a 
body circling on any orbit round the sun would move when at the 
earth's distance from him, unless its orbit were very eccentric and the 
aphelion close by the earth's orbit. Bodies travelling from outer space 
toward the sun cannot by any possibility become satellites of the earth, 
because they would always have a velocity greater than that which her 
attraction can master. Even in the rare event of their grazing her 
atmosphere, and so losing a large share of their velocity, they could not 
become permanent satellites of hers, because, returning to the scene of 
encounter, they would lose yet a larger share of their velocity, and so 
must be brought, and that soon, to her surface. 



METEORS AND COMETS. 21 g 

uncommon, that the number of cometic systems thus 
forced to own Jupiter as their centre of attraction 
must be relatively few. But in another way the plan- 
et does exhibit his power as a comet-ruler, making 
comets recognize him as a sort of subordinate master, 
the sun being their primary ruler. When comets 
coming from outer space pass near enough to Jupiter, 
he sways them so markedly from the orbit they are 
pursuing that the scene of encounter becomes the 
aphelion of their orbit, or nearly so. Thence they 
pass on their new orbit to their perihelion, returning 
again presently to the scene of their encounter with 
Jupiter, and so revolving in an orbit having its 
aphelion close by the orbit of Jupiter, until haply the 
giant is again near the scene of encounter at the mo- 
ment when the comet comes back to it. In this case 
a fresh struggle takes place, the overmastering attrac- 
tion of the planet necessarily prevailing, and the comet 
being often dismissed on a new orbit, whose perihelion, 
instead of its aphelion, lies close by the orbit of Ju- 
piter. , 

Now, we know that such events as these must be 
of frequent occurrence as Jupiter sweeps swiftly round 
on his orbit. For we recognize several comets which 
have evidently been compelled by Jupiter to take up 
such orbits as I have spoken of — a family of comets, 
in fact, including Encke's, Faye's, and Brorsen's com- 
ets, Winnecke's short-period comet, and several others. 
"We judge further, from the laws of probability, that, 
for each discovered comet of this family, there must 
be thousands which have escaped detection. So thai 



220 OTHER WORLDS THAN OURS. 

around the orbit of Jupiter (if not around Jupiter 
himself) there cling the aphelia of myriads of ecmetic 
orbits, whose perihelia lie at all conceivable distances 
from the sun less than the distance of Jupiter. 

Saturn also has his family of comets ; so also have 
Uranus and Neptune. The comet associated with the 
November meteors belongs indeed to the Uranian 
comet-family, and the epoch (126 a. d.) has even been 
pointed out when this comet fell under the dominion 
(subject always to the sun's superior control) of that 
distant planet. 

And here I may refer to a view which 1 have long 
entertained respecting the purposes which meteoric 
and cometic systems have fulfilled in the past history 
of the solar system.* "We know that the materials 
composing meteors, and we conclude, therefore, that 
those composing comets, do not differ from those 
which constitute the earth and sun, and presumably 
the planets also. Therefore, under the continual rain 
of meteoric matter, it may be said that the earth, sun, 
and planets, are growing. Now, the idea obviously 
suggests itself, that the whole growth of the solar 
system, from its primal condition to its present state, 
may have been due to processes resembling those 

* Since the present chapter was written, I find that the hypothesis 
ftere put forward has in a general way been touched on by more than 
one astronomer and physicist. I believe, however, that here, for the 
first time, it has been associated with the chief features of the solar 
rystem. It was suggested in note b (Appendix) to my treatise on Sat- 
urn. But, as a matter of fact, when that note was written, as also when 
those passages were published in which the same hypothesis is touched 
by other authors, the decisive evidences in favor of the theory were 
wanting. 



METEORS AND COMETS. 22 \ 

which we now see taking place within its bounds. It 
is of course obvious that, if this be so, the number 
of meteoric and cometic systems must have been 
enormously greater originally than it is at present. 
Countless millions of meteoric systems, travelling in 
orbits of every degree of eccentricity and inclination, 
travelling also in all conceivable directions around the 
centre of gravity of the whole, would go to the making 
up of each individual planet. A marked tendency to 
aggregate around one definite plane, and to move in 
directions which, referred to that plane, corresponded 
to the present direction of planetary motion, would 
suffice to account for the present state of things. The 
effect of multiplied collisions would necessarily be to 
eliminate orbits of exaggerated eccentricity, and to 
form systems travelling nearly on the mean plane of 
the aggregate motions, and with a direct motion. 
Further, where collisions were most numerous, there 
would be found not only the most circular resulting 
orbits, not only the greatest approach to exact coin- 
cidence of such orbits with the mean plane of the 
whole system, but the bodies formed out of the result- 
ing systems would there exhibit rotations coinciding 
most nearly with the mean plane of the entire sys- 
tem.* 

It seems to me that, not only has this general view 

* This conclusion depends on a well-known law of probability. It 
may be thus illustrated : If we have in a bag a hundred white and a 
hundred black balls, and take out at random a number of balls, then 
the larger that number, the more nearly (in all probability) will the 
number of black and white balls included in it approach to a ratio of 
equality. 



222 OTHER WORLDS THAN OURS. 

of the mode in which our system has reached its pres- 
ent state a greater support from what is now actually 
going on than the nebular hypothesis of Laplace, but 
that it serves to account in a far more satisfactory 
manner for the principal peculiarities of the solar sys- 
tem. I might indeed go further, and say that, where 
these peculiarities seem to oppose themselves to La- 
place's theory, they give support to that which I have 
put forward. 

For example, what is there in the nebular hypothe- 
sis which affords even a general explanation of the 
strange varieties of size observed in the planetary sys- 
tem ? How can that hypothesis be reconciled with 
the remarkable variations of inclination observed 
among the planets, or with the retrograde and almost 
perpendicular motion of the satellites of Uranus ? 
Nor, again, is the hypothesis consistent with the ob- 
served peculiarities of motion of those meteoric sys- 
tems which we must now regard as regular members 
of the solar system. 

Now, according to the hypothesis I have put for- 
ward above, a general explanation of all these matters 
is at once suggested. Let us consider : 

In the neighborhood of the great central aggre- 
gation which would undoubtedly result from the mo- 
tions of such meteoric systems as I have considered, 
all the motions would be very rapid. They would, in 
fact, resemble the motions now actually observed in 
the sun's neighborhood. Here, therefore, subordinate 
aggregations would form with difficulty, since they 
would have small power of overruling meteoric sys- 



METEORS AND COMETS. 223 

terns rushing with so great a velocity past them. In 
the sun's immediate neighborhood, then, we should 
expect to find relatively small planets ; and we do ac- 
cordingly find that Mercury, nearest to him, is the 
smallest of the planets, Yenus larger, and the earth 
(yet farther away) not only larger than Yenus, but 
adorned with an attendant satellite. 

Now, at a much greater distance from the sun the 
meteoric motions would be so much less, that here, 
supposing only a suitable mean density of aggrega- 
tion, it would be possible for subordinate centres of 
aggregation of far greater magnitude to form. These 
centres would increase in importance as they swept 
round the central aggregation, continually gathering 
fresh recruits. Indeed, though, as now, they would 
not be able to prevent the major part of the materials 
rushing from outer space toward the sun from aggre- 
gating round him, they would still gather in no in- 
considerable portion of those materials. "Where the 
largest portion would be gathered would depend on 
the way in which (taking a general view of the sys- 
tem) the quantity of material increased toward the 
neighborhood of the centre. For clearly, while dis- 
tance from the sun would increase the facility with 
which materials would be gathered in — since the sun's 
influence would diminish with distance, it would also 
affect the quantity of material available — since, from 
a very early period, the system must have begun to 
show an appearance resembling that now presented 
by the zodiacal light, that is, a general increase of 
density toward the centre. 



224 



OTHER WORLDS THAN OURS. 



Assuming that the region of maximum aggrega- 
tion was that where the influence of the ruling centre 
first became so far diminished with distance as to ren- 
der the formation of a great subordinate aggregation 
possible, we should have the innermost of the outer 
series of planets also the most bulky ; and next, with- 
in that giant planet we should find a relatively barren 
space, cleared of material not only by the sun's still 
powerful influence, but also by the influence of this 
first important subordinate aggregation. The initial 
assumption is, in itself, at least not improbable, and, 
having once admitted it, we find an explanation of the 
giant mass of Jupiter, of the comparative poverty of 
material just within the orbit of Jupiter, and hence, of 
the condition of the asteroidal zone, and of the small- 
ness of the planet Mars next within that zone — though 
this planet far outweighs (according to Leverrier's es- 
timate) the united mass of all the asteroids. Beyond 
the orbit of Jupiter, we should expect (after passing 
an enormously wide space, bare of worlds) to find still 
a great abundance of material, and an even greater 
facility in the aggregation of that material. Thus the 
existence of the planet Saturn, next in importance to 
Jupiter, and surpassing him in the complexity of his 
attendant system, is accounted for ; yet farther away 
we look for and find still an abundance of material, 
and that material somewhat more uniformly strewn, 
while the sun's small influence is indicated by the ex- 
istence of satellites, of which doubtless many more will 
one day be discovered by astronomers. 

And as to the rotations of the various members of 



METEORS AND COMETS. 225 

the solar system we find some account, necessarily not 
exact, given by this theory. I have mentioned above 
the results to be looked for ; those observed are closely 
accordant with that view. Thus the sun, the largest 
member of the system, and specially preeminent with- 
in its inner division, rotates on an axis inclined but 
about seven degrees to the mean plane of the system. 
Mars, the least member of this system, has an inclina- 
tion of no less than twenty-eight degrees ; the larger 
earth an inclination of but twenty-three degrees. The 
inclinations of Yenus and Mercury are undetermined ; 
they may be expected to be large, not merely on ac- 
count of the smallness of these bodies, but on account 
of their proximity to the sun. Of the outer division 
of the system, Jupiter, the largest, has an inclination 
of little more than three degrees ; Saturn has a very 
considerable inclination (more than twenty-six de- 
grees) ; Uranus has an inclination which may be de- 
scribed as actually greater than ninety degrees, since 
he rotates backward with his equator inclined seventy- 
six degrees to the ecliptic. And lastly, if the obser- 
vations hitherto made on Neptune's satellites are to 
be trusted, this planet, probably, rotates in a retrograde 
manner, his equator being inclined some twenty-six 
degrees to the horizon ; so that, to render the compari- 
son between his rotation and that of the other mem- 
bers of the solar system complete, he may be said to 
rotate in a direct manner with his equator inclined 
some one hundred and fifty-four degrees to the ecliptic. 
The great inclination and eccentricity of many of 

the asteroidal orbits are also accounted for more satis- 
15 



i2 6 OTHER WORLDS THAN OURS. 

tactorily by this theory than by the nebular hypothe« 
sis. In fact, there is an absolute incorrectness in the 
assertion that the smallness of the asteroids can (on 
the ordinary view of their origin) explain the relatively 
irregular nature of their motions. Their minuteness 
doubtless brings them more under the disturbing influ- 
ence of Jupiter than a single massive planet at the 
same distance from the sun would be. But the attrac- 
tions of Jupiter can have no influence in causing the 
asteroids to depart so widely as they do from the eclip- 
tic, since his path lies quite close to the ecliptic, and 
even nearer to the mean plane of the solar system. 
But bodies formed as the asteroids are supposed to be, 
according to the hypothesis I have suggested, would ne- 
cessarily exhibit a much greater variety of motion than 
would be recognized in the case of the larger planets. 
Another point in which, as I conceive, my hypoth- 
esis is more satisfactory than the nebular one, consists 
in the fact that it suggests an explanation of the pecu- 
liarities observed in the planetary periods. Prof. Kirk- 
wood's researches into the various relations of commen- 
surability presented among the periods of planets and 
satellites, and the known effects of commensurability 
in encouraging the accumulation of planetary pertur- 
bations, will at once suggest to the mathematical 
leader the way in which a system, forming in such a 
manner as I have imagined, might be expected to ex- 
hibit the presence of law as regards distances and pe- 
riods. I know of nothing in the nebular hypothesis 
which encourages the belief that a system framed as 
Laplace conceived the solar system to be, would ex- 



METEORS AND COMETS. 



227 



hibit any such laws as are found within the planetary 
scheme. 

The hypothesis I have put forward also gets rid of 
that which has always seemed to me the great difficulty 
of the nebular hypothesis. According to the views of 
Laplace, Neptune must have been formed millions of 
ages before Uranus, Uranus as long before Saturn, 
Saturn as long before Jupiter, and so on. Now, we know 
that the appearance of those primary members of the 
solar system which we are best able to study does not 
indicate any such enormons disproportion in the ages 
of the planets, even if it does not indicate that the plan- 
ets were formed nearly at the same era. According to 
my hypothesis, the various processes of aggregation 
would go on simultaneously (just as the influences 
which Jupiter has on comets are now exerted simulta- 
neously with those more powerful influences possessed 
by the sun) ; and though the various orbs formed by 
those processes would not necessarily be completed 
simultaneously, there would be no such enormous dis- 
proportion in their age as is necessary according to the 
theory of Laplace. 

Yet another strong point in favor of this hypothe- 
sis resides in the circumstance that we now have every 
reason to believe that all the planets are constituted of 
the same elements. When it was thought that Jupiter 
might be a watery globe, for instance, there was some 
evidence in favor of Laplace's theory. But we now 
know that Jupiter is not constituted differently, in all 
probability, from the earth and sun, as according to 
Laplace's theory he must have been. Since, then, we 



i 2 8 OTHER WORLDS THAN OURS. 

know that meteors contain the same elements which 
exist in the constitution of sun and planets, we have 
here a very strong argument in favor of the view that 
they have played the important part I have assigned 
to them in the formation of the solar system. 

But, after all, the strongest evidence in favor of the 
hypothesis I have suggested, consists in the fact that 
the processes by means of which I conceive the solar 
system to have been formed, are undoubtedly going on 
before our eyes. There may be little, indeed, in the 
downfall of meteoric showers to suggest the idea of 
world-formation or sun-formation ; little in the present 
aspect of the zodiacal light or of the solor corona, to 
present to the mind's eye a picture of that vaster 
agglomeration of meteoric and cometic systems, all 
speeding with inconceivable velocities on their inter- 
lacing orbits, which I imagine to have been the era- 
bryon of the solar scheme. But sun and planets are 
growing, however slowly, as the meteoric hail falls 
continuously upon them; the zodiacal light and the 
solar corona are doubtless due to the existence of 
meteoric systems, resembling (however relatively in- 
significant) those which I have pictured as the materi- 
als of the planetary scheme. In the Saturnian rings, 
also, which have been proved by the researches of 
Maxwell and others to consist of multitudes of dis- 
crete bodies, we have evidence of the same sort in the 
case of a subordinate centre of aggregation. So that 
we have a form of evidence which was wanting in the 
case of the nebular hypothesis, in favor of this other 
hypothesis, by which, as in Laplace's, the present state 



METEORS AND COMETS. 229 

of the solar system is regarded as the result of a pro- 
cess of development, and not of special creative fiats 
of the Almighty. 

In this last respect, the hypothesis I have put for- 
ward will doubtless seem objectionable to those who 
imagine that, in indicating processes according to 
which the solar system may have reached its present 
condition, astronomers are attacking the attributes of 
God. This will be the more unfortunate, because 
those who entertain this strange view may be re- 
garded as probably so far beyond the reach of argu- 
ment as to be unlikely ever to abandon their objection. 
Otherwise, it might avail to point out that, as, in all 
that surrounds us, we find God acting through second 
causes, we can have no reason for assigning limits to 
the range of space or time within which He so acts ; 
that is, we can have no reason for believing that we 
can point to a time when He acted directly upon the 
universe : and further, that it gives an altogether high- 
er idea of that wisdom which must, in any case, be 
far above our conceptions, to regard the laws of God 
as so perfect that they operate always to work out His 
will — without the necessity of special interference on 
His part — than to see His hand directly operative in 
all the phenomena of the universe. 



CHAPTER X. 



OTHER SUNS THAN OTJES. 



We are now to venture into regions where we shall 
no longer have clear lights to guide us. Tremendous 
as are the dimensions of the solar system, the widest 
sweep of the planetary orbits sinks into insignificance 
compared with the distances which separate from us 
even the nearest of the fixed stars. From beyond 
depths which the human mind is utterly unable to 
conceive there come to us the rays of light which 
myriads of those orbs are pouring forth, and it is from 
the lessons taught us by these light-rays that we are 
to form our ideas concerning the nature of the orbs 
which emit them. Yery carefully and cautiously must 
we proceed, if we would avoid being led into vain 
imaginings. It will but mislead us to pass a single 
step beyond the path which is dimly lighted for us, 
and yet that path is so narrow and so obstructed with 
difficulties, that we find ourselves continually tempted 
to leave it, and to venture forward on the alluring and 
easy paths which speculation opens out on every hand 
around us. 



OTHER SUNS THAN OURS. 251 

And yet we may well remain content to listen only 
to the teachings of known facts. Even so restraining 
ourselves, we have in reality a wide and noble domain 
to explore. Facts which seem severally unimportant, 
are found, when considered as parts of a grand whole, 
to indicate relations so impressive and so interesting, 
that the revelations of the telescope within the solar 
system are apt to seem commonplace beside them. 
We have, in fact, to consider no longer the structure 
of a system — the architecture of the universe is our 
theme. 

Let us examine carefully the evidence which sci- 
ence has gathered together for us, endeavoring at each 
step to gain the full amount of knowledge the several 
facts involve, while, at the same time, cautiously refrain- 
ing from any attempt to overstep the bounds indicated 
by our evidence. 

In the first place, let us consider what may be 
learned from the analogy of the solar system. The 
study is an inviting one, since the discoveries on which 
we are to found our views have been made so recently, 
that the subject has all the charm of novelty and fresh- 
ness, while it involves the consideration of the soundest 
and most instructive mode of pursuing our researches. 

We have seen in the solar system a variety and 
complexity of structure, such as, half a century ago, 
few astronomers would have thought of ascribing to 
it. When Sir William Herschel began that noble 
series of researches amid the sidereal depths by which 
his name has been rendered illustrious, he saw in the 
solar system a scheme very different indeed from that 



232 



OTHER WORLDS THAN OURS. 



which is presented to our contemplation. He beheld 
a vast central body, surrounded by a limited number 
of orbs, some of which were the centres of subordinate 
schemes of greater or less extent. "When we have 
added the ring of Saturn as the only formation dif- 
fering from planets and satellites in character, and the 
comets few and far between, w T hich seemed rather acci 
dental tributaries of the sun than regular members of 
his family, we have considered all the features which 
the solar system, as known in Sir "William Herschel's 
day, presented to the contemplation of astronomers. 

With us it is very different. We see that there 
exists within the solar system a variety of size and 
structure, of motion, arrangement, and aggregation, 
which is already inconceivable, and yet doubtless but 
faintly shadows forth the real complexity and richness 
of the scheme swayed by our sun. Perhaps it is in 
considering the solar system in the particular light in 
which, in this treatise, I have had occasion to present 
it, that this wonderful variety of conformation is made 
most strikingly apparent. But, apart from all specu- 
lative theories, there can be no doubt that the solar 
system presents to us a subject of study amazing in 
itself, but most amazing when we regard it as supply- 
ing the analogies which are to guide us in forming our 
views respecting the sidereal system. Besides the fam- 
ily of planets circling round the sun, besides the sys- 
tem of dependent orbs which circle round the planets, 
we see a zone in which independent planets circle by 
hundreds, perhaps even by myriads, around the solar 
orb; we see the ring of Saturn composed of thousands 



OTHER SUNS THAN OURS. 233 

of tiny bodies ; we see the meteoric systems in count- 
less hosts ; we see the comets of our scheme in mill- 
ions on millions ; and less certainly, but still not in- 
distinctly, we recognize the existence of a multitude 
of new and hitherto unsuspected forms of matter 
within the circle of our sun's attraction. 

What opinion, then, are we to form — even here, at 
the very outset of our inquiry — respecting the sidereal 
scheme of which our sun forms but a unit ? Surely 
it would be to lose sight of the significant lesson 
taught us by the solar system, it would be to forget 
how sure and safe a guide the greatest of modern as- 
tronomers found in the teachings of analogy, to adopt 
the same view now which that great astronomer 
adopted a century ago. If, viewing the solar system 
as consisting of discrete orbs, comparable one with 
another in size, and distributed not without a certain 
uniformity around their ruling centre, Sir William 
Herschel held that the sidereal scheme presented 
somewhat similar relations, surely we, who know cer- 
tainly that the solar system is constituted so differ- 
ently, must adopt a far different view of the sidereal 
scheme also. 

Let us remember that there is here — so far as our 
respect and admiration for Sir William Herschel are 
concerned — a choice between two courses. Assuming, 
as indeed is just, that the views of our great men are 
not rashly to be thrown on one side, we have to choose 
whether we would rather abandon the views which Sir 
William Herschel formed about facts, or the views 
which he formed about princijjles. If we accept his 



2 34 OTHER WORLDS THAW OURS. 

opinion (or rather, after all, his mere suggestion) that 
the stars are tolerably uniform in magnitude and dis- 
tribution, we must abandon the analogy of the solar 
system. If, on the contrary, we accept Sir William 
HerschePs often-expressed opinion that, in theorizing 
about the unknown, there can be no safer guide than 
the analogy of known facts, we must abandon the 
view (which seemed to him but probable) that the stars 
are distributed with tolerable uniformity throughout 
our galaxy, and are comparable inter se in magnitude 
and splendor. 

There can be no doubt which course is preferable. 
We know certainly that Sir William Herschel was 
often mistaken, as all men must be, in matters of fact ; 
while we know with equal certainty that he owed the 
marvellous success with which he theorized, to his 
adoption of the principle that analogy is the chief and 
the best guide for the student of astronomy. 

We are compelled, then, in our very respect and 
admiration for the greatest astronomer of modern 
times, to regard the constitution of the sidereal system 
as, in all probability, very different from what he 
imagined. 

We must be prepared to expect an infinite variety 
of figure, of structure, of motion, and of aggregation 
throughout the galactic scheme. If some orbs within 
that scheme seem probably to be suns like our own, 
W£ must not be surprised to find others which are 
probably far larger or far smaller. We may look for 
objects differing as much from the suns of the sidereal 
system as the asteroidal zone differs from Saturn or 



OTHER SUNS THAN OURS. 235 

from Jupiter. So that, if we should recognize evidence 
of the existence of clusters of minute stars — a whole 
cluster, perhaps, not equalling in real importance the 
least of the suns of the system — we may accept that 
evidence without any scruples suggested by the im- 
probability of the conclusion to which it points. 
Again, we may expect to find schemes within the si- 
dereal system, differing as much from discrete stars or 
star-clusters as the rings of Saturn differ from the 
primary planets or from the asteroidal zone. So that, 
if we should recognize evidence of the existence of rel- 
atively minute clusters, whose components are either 
so small or so closely aggregated as not to be sepa- 
rately visible even in our most powerful telescopes, 
this evidence may fairly be accepted as accordant with 
the only analogy we have for our guidance. Yet once 
more : we may look for systems differing as much 
from all ordinary star-clusters as the eccentric and far- 
reaching meteor-systems differ from the symmetrical 
rings of Saturn. So that, if we should find evidence 
of strange schemes within the sidereal system, schemes 
presenting every bizarre variety of figure, with strange 
complexities of spiral whorls or outlying branches, 
losing themselves, as it were, in the depths toward 
which they seem to extend — this also need not sur- 
prise us : we need not conclude that here, at any rate, 
we are looking beyond the bounds of the sidereal sys- 
tem, and gazing upon external galaxies, for the anal- 
ogy we have chosen for our guidance teaches us that 
such structures were to be expected within the scheme 
of which our sun is a component. And, finally, if we 



23 6 OTHER WORLDS THAN OCTRS. 

should find reason to assure ourselves that there are 
objects in the depths of space whose very substance 
and constitution are different from those of all other 
objects within the sidereal system, we need by no 
means believe that the objects thus singularly consti- 
tuted belong to, or form, external systems. For the 
millions on millions of comets which form part and 
parcel of the solar system present a precisely analogous 
difference of structure, as compared with the other 
members of that system. 

Having thus replaced the erroneous analogies to 
which — through no fault of his own — Sir "William 
Herschel was led to look for guidance, by the more 
trustworthy analogies which the recent progress of 
astronomy has afforded for our instruction, we may 
proceed to consider the direct evidence we have re- 
specting the constitution of our galaxy. 

In the first place, let us examine the evidence 
which points to the dimensions of the sidereal system. 

That the nearest members of the system lie at 
enormous distances from us is proved by the fact that, 
as the earth sweeps on her vast orbit round the sun, 
no appreciable change is observed in the configuration 
of the star-groups. That a circle having a diameter of 
more than one hundred and eighty millions of miles 
should be swept out year by year as the earth trav- 
erses her orbit, and yet that the surrounding stars 
should exhibit no change of place, is at once the most 
striking and the simplest evidence we have, of the 
enormous scale on which the sidereal system is, con- 
structed. And yet this first obvious fact sinks almost 



OTHER SUNS THAN OURS. 237 

into insignificance when we regard thoughtfully the 
teaching of modern instrumental astronomy. There 
might be a real shifting of apparent position which 
yet the unaided eye would fail to detect, and such a 
change would indicate distances so enormous that the 
mind fails altogether to conceive their real signifi- 
cance. But the exact instruments of modern times 
would exhibit a change of place infinitely more mi- 
nute than any which the unaided eye could recognize. 
If a star shifted by so much as the ten thousandth part 
of the moon's apparent diameter, modern astronomers 
could assure themselves of the change of place. And 
when we remember that in precisely the same propor- 
tion that we increase the exactitude of instrumental 
observation we increase also the significance of the 
stars' apparent fixity of position, it will be seen at once 
how astounding is the lesson conveyed by the fact 
that all but a very few indeed of the stars remain abso- 
lutely unaffected — even under the most powerful in- 
strumental examination — by the enormous range of 
the earth's orbital motion. 

We can roughly estimate the distances of the few 
stars which are thus affected, and thence — on the hy- 
pothesis that the intrinsic brilliancy of their light is 
the same as the sun's — we may form some idea of 
their dimensions. I shall, however, only apply this 
process, in detail, to a single case, because my present 
object is rather to indicate in a general way the scale 
on which the sidereal system is constructed, than to 
enter at length on the more exact details which find 
their place in ordinary treatises on astronomy. 



238 OTHER WORLDS THAN OURS. 

The star Alpha Centauri is one of the brightest in 
the heavens, Sirins and Canopns alone surpassing it 
in splendor. But it is not its exceptional brilliancy 
alone which led astronomers to regard it as likely to 
afford evidence of an apparent change of place corre- 
sponding to the earth's real change of place as she 
sweeps round her orbit. Of course, the brightest 
stars are presumably the nearest ; but there is another 
indication of proximity at least equally important. 
The so-called fixed stars are in reality slowly moving 
onward on definite courses — slowly, that is, in appear- 
ance, though in reality their motions are doubtless 
inconceivably rapid. Now, these motions, the proper 
motions of the stars, as they are called, are as yet very 
little understood. "We know only that the whole of 
the galactic system is astir with life, but whither the 
orbs are severally tending we are not yet able to say. 
Nor do we know what portion of the stellar motions 
may be due to the undoubted proper motion of our 
own sun through space. This, however, may be re- 
garded as certain, that, until we know something re- 
specting the laws which regulate the stellar move- 
ments, we must regard the magnitude of a star's 
motion as probably an indication of relative proxim- 
ity. Precisely as a man walking at a great distance 
from us appears to move much more slowly than one 
who is walking at the same rate close by, so the ap- 
parent rate of a star's motion is diminished in propor- 
tion to the star's distance from us. When, therefore, 
it was found that the star Alpha Centauri is moving 
more rapidly than other stars, this fact, combined with 



OTHER SUNS THAN OURS. 239 

the great lustre of the star, led astronomers to suspect 
that it must be comparatively near to us. 

Observations, made to determine whether the star 
shows any sign of an annual change of place corre- 
sponding to the earth's annual orbital motion, were 
rewarded by the detection of a very appreciable dis- 
placement. In fact, owing to the motion of the earth, 
each year, in a nearly circular orbit one hundred and 
eighty million miles in diameter, the star Alpha Cen- 
tauri appears to trace out each year a minute oval path 
on the celestial sphere, the greater axis of the oval be- 
ing equal in length to about -^-g-g-th part of the moon's 
apparent diameter.* 

It follows from this that, in round numbers, the 
distance of Alpha Centauri from us is about twenty 
millions of millions of miles. The distance of the 
earth from the sun shrinks into insignificance beside 
this enormous gap. Even Neptune, though circling 
round the sun at a distance three hundred times vaster 
than that which separates us from that luminary, is 
yet relatively so much nearer than Alpha Centauri, 
that a sun filling the whole orbit of Neptune would 
appear, as seen from that star, but about one-ninth as 
large as the sun appears to us. 

Now let us consider what dimensions we may as- 
sign to Alpha Centauri, on the assumption that the 
surface of this star emits a light as brilliant as that 

* It hardly need be mentioned, perhaps, that this motion being 
superadded to the star's more considerable proper motion, the path 
which the star seems really to follow is a looped one, the size of each 
loop being small in comparison with the distance between successive 
loops. 



24-0 



OTHER WORLDS THAN OURS. 



which proceeds from the photosphere of our own sun. 
"We must not neglect the consideration that the star is 
double — the companion emitting perhaps about one- 
sixteenth as much light as the primary.* The distance 
of Alpha Centauri is equal to about two hundred and 
thirty thousand times that which separates us from the 
sun. Therefore, if removed to the star's distance, the 
sun would shine with only 62 , 900> 1 000>000 th part of his present 
brilliancy. Now, according to the most careful esti- 
mates of the brilliancy of Alpha Centauri, the light 
we receive from that star is about 16i9SOi 1 000[000 t1i of that we 
receive from the sun.f It follows, therefore, that the 
star emits about three times as much light as the sun ; 
and therefore, so far as the emission of light is a crite- 
rion of size, the star may be regarded as considerably 
larger than our own sun. In fact, reducing the total 
light of the pair by one-sixteenth, we find that the 
primary must still emit about three times as much 
light as the sun, and therefore the diameter of the 
star, as thus estimated, would appear to exceed our 
sun's in the proportion of about seventeen to ten. 

We have here, then, clear and decisive evidence in 
favor of the view that among the fixed stars there are 
orbs which may be regarded as veritable suns, worthy 
to be the ruling centres of schemes as noble as the solar 

* Sir John Herschel, observing the star with his twenty-feet reflector, 
thought the secondary brighter than it is usually considered. I cannot 
but think that, for a comparison of this sort, smaller telescopes may more 
safely be trusted. 

f This estimate is founded on Sir John Herschel's comparison be- 
tween the light of the star and that of the full moon, and Zollner'a 
comparison between the light of the full moon and that of the sun. 



OTHER SUNS THAN OURS. 



241 



gystein. For we know quite certainly that the greater 
number of the first-magnitude stars are very much 
farther from us than Alpha Centauri, with which, how- 
ever, they are fairly comparable in brilliancy : so that 
they may be regarded as for the most part at least 
equal to that star in size and mass. Sirius and Canopus, 
indeed, must far surpass Alpha Centauri. The latter, 
though more than thrice as bright, exhibits no appre- 
ciable change of position as the earth circles round the 
sun. Sirius, which is more than four times brighter 
than Alpha Centauri, shows an annual change of posi- 
tion which certainly does not exceed one-fourth of that 
star's. It is therefore four times farther from us than 
Alpha Centauri. and, did it emit no greater amount 
light, would appear to shine with but one-sixteenth 
of that star's lustre. As in reality it is four times as 
bright, the real amount of light it emits must exceed 
that of Alpha Centauri no less than sixty-four times, 
and that of our own sun no less than one hundred and 
ninety-two times. So that, judged from this indication 
alone, the diameter of Sirius mav be held to exceed 
that of our sun in the proportion of about fourteen to 
one, an estimate which assigns to Sirius a diameter of 
nearly twelve million miles, and a volume two thou- 
sand six hundred and eighty-eight times as large as the 
sun's. 

But, on the other hand, still confining our atten- 
tion to this method of estimating magnitude, we find 
reason for believing that many of the visible stars 
must fall far short of our sun in magnitude. The 
sixth-magnitude double star, 61 Cygni, has been found 
16 



Z 4 2 



OTHER WORLDS THAN OURS, 



to be nearer to us than Sirius, and about three timea 
as far from us as Alpha Centauri. Now, we may as- 
sume that each component sends us about one-hun- 
dredth part of the light we receive from Alpha Cen- 
tauri ; it follows that the latter star, if removed to 
the distance at which 61 Cygni lies from us (when its 
lio-ht would of course be diminished to one-ninth of its 
present value), would outshine either component of 
that double star more than eleven times ; hence (on 
the assumption that brightness is a fair measure of real 
dimensions), each component has a diameter less than 
one-third that of Alpha Centauri. We may roughly 
estimate the volume of each at about -^ th of that of 
the latter star. So that, remembering what has al- 
ready been shown respecting the relation between 
Alpha Centauri and our sun, the two suns which form 
the double star 61 Cygni would each have a diameter 
equal to about -J-Jths of the sun's, and a volume 
equal to about -^-ths. The sum of their volumes would 
be therefore about one-third of his ; and it will presently 
appear that a perfectly distinct mode of estimation 
tends to show that the sum of their masses bears about 
the same proportion to the sun's mass. 

But here at once we have evidence that there is a 
very wide range of magnitude among the fixed stars. 
We have seen reason to believe that Sirius is twenty- 
six hundred and eighty-eight times as large as the 
sun, while each of the suns forming the double star 
61 Cygni would appear to have a volume less than 
one-fifth of our sun's, and therefore less than 13 | 00 th 
of -the volume of Sirius. So that, by considering 



OTHER SUNS THAN OURS. 2+3 

only three cases, we have found tolerably clear evi- 
dence of a range of variety in volume, reminding us 
forcibly of that which we recognize in the solar system. 
We cannot suppose that these three cases, which have 
been selected at random — so far as the question of vol ■ 
uuie is concerned — indicate any thing like the real 
limits within which the fixed stars differ in magnitude. 
So that we may confidently accept, as the most prob- 
able conclusion from the evidence before ns, that the 
range of real magnitude among the fixed stars is very 
far greater than Sir "W". Herschel was led to anticipate, 
when, nearly a century ago, he began his researches 
into the sidereal system. 

But it is not sufficient that we should thus form 
an estimate of the nature of the fixed stars, from the 
amount of light they send to us. It is desirable — and 
fortunately it is practicable — to obtain information as 
to the absolute mass or weight of some of the fixed 
stars, and further to ascertain of what substances they 
may be composed, and in what condition those sub- 
stances may exist. Mere lights, however glorious, or 
however wide the sphere within whicb they displayed 
their splendors, would not be fit to sway the motions 
of orbs resembling those which circle around our sun. 
Nor would such lights serve to indicate to the astron- 
omer that, out yonder, myriads of millions of miles 
beyond the extreme limits of the solar system, there 
exist materials suited to form the substance of worlda 
resembling our own. 

It seems a strange circumstance that astronomers 
should be able to form a more exact and trustworthy 



2 44 OTHER WORLDS THAN OURS. 

estimate of the weight of certain fixed stars than they 
can hope to form respecting the volume of any of those 
bodies. Let us consider what evidence we have on 
this point. 

I have spoken of the star 61 Cygni as a double 
star. The smaller star shows very clear indica- 
tions of orbital motion around its primary. That the 
two are associated together, and not merely seen, as it 
were by an accident, nearly in the same line of view, 
is indeed certain, because that peculiarly large prop- 
er motion already referred to is shared in by both. 
But many stars may be physically associated, and yet 
the distance really separating them may enormously 
exceed that by which they seem to be separated — 
since the line joining them is not necessarily square 
to the line of sight. The components of the star 61 
Cygni have been carefully watched, however, and their 
motions show that they are circling around each other. 
The distance separating them is probably about half 
as large again as the distance of Neptune from the 
sun. 

The period of revolution appears to be about five 
hundred and twenty years, which is more than three 
times as great as the period of Neptune. Now, we 
know that a planet placed at distance from the sun, 
equal to that which separates the components of 61 
Cygni, would occupy a much less period than five hun- 
dred and twenty years in completing a revolution ; in 
fact, its period would be about three hundred years. 
Hence it follows that the components of 61 Cygni are at- 
tracted together less forcibly than Neptune is attracted 



OTHER SUNS THAN OURS. 245 

toward the sun, and therefore that the sum of their 
masses must be less than the sun's mass. It is easy 
to compute the actual proportion, and we find accord- 
ingly that the two components of 61 Cygni, taken to- 
gether, weigh about one-third as much as our sun.* 

The star Alpha Centauri is also a binary system, 
and, though it has not been so systematically observed 
as 61 Cygni, some astronomers believe that its period 
has been even more satisfactorily determined. Indeed, 
there are peculiarities in the motion of 61 Cygni, 
which, without throwing doubt on the general conclu- 
sions deduced above, yet suggest that a third (proba- 
bly opaque) orb affects the motions of the other two. 
From a careful comparison of all the observations 
made in recent times on Alpha Centauri, Mr. Hind 
has assigned to the components a period of revolu- 
tion of about eighty-one years, and a mean distance of 
13.6 seconds of arc, corresponding to a real distance 
exceeding the earth's distance from the sun some fif- 
teen times. Since a planet placed at this distance 
from the sun would occupy less than sixty years in 
completing a revolution around that body, it follows 
that the mass of the two components of Alpha Cen- 
tauri must be less than that of the sun. This result 
(if the data be considered trustworthy) would indicate 
a considerable difference between the condition of the 
star and that of our sun ; for we have seen that the 

* It may easily be shown that, if a pair of bodies, circling around 
each other at a certain distance, take a certain time T in effecting a 
revolution, while another pair at the same distance take a time £, the 
former pair, taken together, hare a weight which bears to the weight of 
the latter pair the ratio of f to T 2 . 



246 OTHER WORLDS THAN OURS. 

star gives out much more light than the sun. How 
ever, I believe that many years must elapse before we 
can regard the period of Alpha Centauri as satisfac- 
torily determined. 

Still, we have conclusive evidence in this case, as 
in that of the star 61 Cygni, that the component 
stars are really bodies of enormous weight, and conse- 
quently well fitted to sway the motions of families of 
planets. We conclude, therefore, that the fixed stars 
generally are suns, not mere lights ; and, further, we 
are led to believe that there must be a general similar- 
ity in the conditions under which these bodies and our 
own sun emit light. And thus we are led to recognize 
other stars also — though as yet unweighed — as mas- 
sive orbs, not merely supplying light to other worlds 
travelling around them, but regulating by their attrac- 
tive influences the orbital motions of their dependent 
worlds. 

But we owe to the revelations of the spectroscope 
the complete proof of these matters, besides evidence 
on other and equally interesting points. 

It had long been known that the spectra of the fixed 
stars present a general resemblance to the solar spec- 
trum, though of course very much fainter, and that 
dark lines can be seen in these spectra, some of which 
correspond with those in the sun's spectrum, while 
others seem to be new. So soon as the great discovery 
effected by Kirchhoff had been announced, it was seen 
at once that these dark lines in the stellar spectra af- 
ford the means of determining the constitution of the 
stars. It was only necessary that these lines should 



OTHER SUXS THAN OURS. 2 47 

be identified by their correspondence with the lines 
belonging to known elements, in order to prove that 
these elements exist in the substance of the star. But, 
although the principle on which researches were to be 
conducted was sufficiently simple, many difficulties 
had to be encountered. Indeed, the attempts made 
by Airy, Secchi, and Rutherford, to solve the problem 
of determining the constitution of the stars by means 
of spectroscopic analysis, were unsuccessful ; and it 
was not until Prof. Miller and Mr. Huggins commenced 
their famous series of researches that the problem can 
be said to have been fairly mastered. 

Even in the hands of these eminent physicists the 
work was difficult, and its progress tedious. The 
weather necessary for the successful prosecution of so 
delicate a method of inquiry does not often prevail in 
our variable climate. The comparison between the 
dark lines in the stellar spectra and the bright lines 
belongino; to various elements was not onlv a delicate 

CD CJ «/ 

and laborious task, but was singularly painful to the 
eyes. And other difficulties, into which I have not 
space to enter here, had to be encountered and ever 
come. 

But, undeterred by these difficulties, the two physi- 
cists persevered in their researches,' and were rewarded 
by results so interesting and important that their dis- 
covery may be said to constitute the most remarkable 
era in the history of sidereal research since the com- 
pletion of the star-gaugings of the elder Herschel. 

Two bright stars, Betelgeux, the leading brilliant 
of Orion, and Aldebaran, the chief star of Taurus, 



2 4 8 OTHER WORLDS THAN OURS. 

were examined with special care. Mr. Huggins re- 
marks that the spectra of these stars are as rich in 
lines as the solar spectrum itself. The places of no 
less than eighty lines in the spectrum of Betelgeux 
were accurately measured, while as many as seventy 
lines had their places assigned to them in the spectrum 
of Aldebaran. 

With respect to the former spectrum, Mr. Huggins 
remarks that it is most complex and remarkable. 
" Strong groups of lines are visible, especially in the 
red, the green, and the blue portions," a peculiarity, it 
may be remarked in passing, which serves to account 
for the well-marked orange-color of this star. 

Now, here already we have very decided evidence 
as to the nature of the star ; since the very fact that 
its spectrum presents the same general appearance as 
the solar spectrum, proves conclusively that the star is 
an incandescent body, whose light comes to us through 
certain vapors corresponding to those which surround 
the sun. Nor should we be able to regard the star ac 
other than a sun, even though none of the elements 
known to us should appear to be present in its sub- 
stance, or in the vapors surrounding it. For, clearly, 
we have no reason for believing that worlds can be 
formed out of those elements only with which we are 
acquainted, unless we find, as we proceed, that those 
elements actually do compose the suns which form the 
sidereal system. Of course, if this shall appear to be 
the case, our conclusions respecting the nature of the 
stars will be very much strengthened. 

Now, when Prof. Miller and Mr. Huggins com- 



OTHER SUNS THAN OURS. 249 

pared the lines in the spectrum of Betelgeux with the 
bright lines of certain terrestrial elements, they found 
that some of these elements do actually exist in the 
vaporous envelope of the stars. Thus, sodium, mag- 
nesium, calcium, iron, and bismuth, are present in 
Betelgeux. The lines of hydrogen, which are so well 
marked in the solar spectrum, are not seen in the spec- 
trum of Betelgeux. We are not to conclude from this 
that hydrogen does not exist in the composition of the 
star. We know that certain parts of the solar disk, 
when examined with the spectroscope, do not at all 
times exhibit the hydrogen lines, or may even present 
them as bright instead of dark lines. It may well be 
that in Betelgeux hydrogen exists under such condi- 
tions that the amount of light it sends forth is nearly 
equivalent to the amount it absorbs, in which case its 
characteristic lines would not be easily discernible. 
In fact it is important to notice generally, that, while 
there can be no mistaking the positive evidence af- 
forded by the spectroscope as to the existence of any 
element in sun or star, the negative evidence supplied 
by the absence of particular lines is not to be certainly 
relied upon. 

In the case of Aldebaran the two physicists were 
able to establish the existence of sodium, magnesium, 
hydrogen, calcium, iron, bismuth, tellurium, antimony, 
and mercury, in the vapors surrounding the star. 

Besides these stars, fifty others were examined. 
The brilliant Sirius exhibits a spectrum of great beau- 
ty, though the low altitude which this star attains in 
our latitudes rendered the observation of the finer 



* 5 c 



OTHER WORLDS THAN OURS. 



lines exceedingly difficult. But the two physicists 
were able to show that sodium, magnesium, hydrogen, 
and probably iron, exist in this gigantic sun. 

All the stars examined exhibit spectra crossed by 
numerous lines ; and, in a great number of the spectra, 
lines belonging to known terrestrial elements were de- 
tected. 

And now let us consider the general bearing of 
these interesting discoveries. 

In the first place, we are forced to recognize in the 
stars real suns, not mere lights. Doubtless Dr. Whe- 
well did well in pointing out that astronomers had no 
right to regard the stars as suns, until they had some 
evidence that these orbs resemble the sun in other re- 
spects than in size, mass, or luminosity. And as in 
his day it appeared altogether unlikely that such evi- 
dence should be obtained, a real limit seemed placed 
to the speculations men might form as to the existence 
of other planetary systems besides those which circle 
around the sun. 

But now we have precisely that evidence which 
Whewell required. We see that the stars are consti- 
tuted in the same general way as the sun, and that, 
further, they even contain elements identical with 
those which exist in his substance. There is not in- 
deed in every case, perhaps there may not be in any 
case, an exact identity of composition between star and 
sun, or between star and star. But this was no more to 
have been looked for than an exact identity of physi- 
cal habitudes among the members of the solar system. 
That general resemblance of structure which indicates 



OTHER SUNS THAN OURS. 2 $\ 

a general resemblance in the purposes which the ce- 
lestial bodies are intended to subserve, is undoubtedly 
evident, when we compare the stars either with our 
Bun or with each other. 

I have already spoken of the conclusions to be 
drawn from the existence of the same materials in the 
substance of the sun that exist around us on this 
earth. I have shown that we are compelled to regard 
this general resemblance of structure as sufficient to 
prove that the other planets resemble the earth, since 
we have no reason to believe that our earth bears an 
exceptionally close resemblance to the sun as respects 
the elements of which she is composed. 

Since, then, we have reason to believe that all the 
planets which circle around the sun are constituted 
of the same materials which exist in his substance, 
though these materials are not necessarily nor proba- 
bly combined in the same proportions throughout the 
solar system, we have every reason which analogy can 
give us for believing that the planets circling around 
Betelgeux or Aldebaran are constituted of the same 
materials which exist in the substance of their central 
luminary. 

Thus we are led to a number of interesting: con- 
elusions even respecting orbs which no telescope that 
man can construct is likely to reveal to his scrutiny. 
The existence of such elements as sodium or calcium 
in those other worlds suggests the probable existence 
of the familiar compounds of these metals — soda, salt, 
lime, and so on. Again, the existence of iron and 
other metals of the same class carries our minds to the 



E 5 2 OTHER WORLDS THAN OURS. 

various useful purposes which these metals are made 
to subserve on the earth. "We are at once invited to 
recognize that the orbs circling around those distant 
suns are not meant merely to be the abode of life, but 
that intelligent creatures, capable of applying these 
metals to useful purposes, must exist in those worlds. 
We need not conclude, indeed, that at the present 
moment every one of those worlds is peopled with in- 
telligent beings, because we have good reason for be- 
lieving that throughout an enormous proportion of 
the time during which our earth has existed as a 
world no intelligent use has been made of the supplies 
of metal existing in her substance. But that at some 
time or other those worlds have been or will be the 
abode of intelligent creatures seems to be a conclusion 
very fairly deducible from what we now know of their 
probable structure. 

But, secondly, apart from the information afforded 
by the spectroscope respecting the materials of which 
the stars are composed, the nature of the stellar spec- 
tra serves to prove most conclusively that the stars, 
besides supplying light to the worlds which circle 
around them, radiate heat also to them. Even if we 
were not certain that elements which are only vapor- 
ized at a very high temperature exist in the vaporous 
envelopes of the stars, yet the very nature of the light 
sent out by the stars indicates that these orbs are in- 
candescent through intensity of heat. "When we find 
that the spectrum of a planet's light resembles the 
solar spectrum, we do not indeed conclude that the 
planet is as intensely heated as the sun, because we 



OTHER SUNS THAN OURS. 253 

know that the planets are not self-luminous. But, in 
the case of self-luminous bodies ]ike the stars, we can 
conclude from the very nature of their spectra that 
these orbs are intensely heated. Of course we are 
rendered absolutely certain of this when we find that 
iron and other metals exist in the form of vapor in the 
stellar atmospheres. 

The vast supplies of heat thus emitted by the stars 
not only suggest the conclusion that there must be 
worlds around these orbs for which those heat-supplies 
are intended, but point to the existence in those 
worlds of the various forms of force into which heat 
may be transmuted. We know that the sun's heat 
poured upon our earth is stored up in vegetable and 
animal forms of life ; is present in all the phenomena 
of Nature — in winds, and clouds, and rain, in thunder 
and lightning, storm and hail ; and that even the 
works of man are performed by virtue of the solar 
heat-supplies. Thus the fact, that the stars send forth 
heat to the worlds which circle around them, suggests 
at once the thought that on those worlds there must 
exist vegetable and animal forms of life; that natural 
phenomena, such as we are familiar with as due to the 
solar heat, must be produced in those worlds by the 
heat of their central sun; and that works such as 
those which man undertakes on earth — works in 
which intelligent creatures use Nature's powers to 
master Nature to their purposes — must go on in the 
worlds which circle around Aldebaran and Betelgeux, 
around Yega, Capella, and the blazing Sirius. 

Recently it has even been found possible to render 



2 5 4 OTHER WORLDS THAN OURS. 

the stellar heat sensible to terrestrial observation, by 
methods which need not here be inquired into. Nay, 
the task of measuring the amount of heat received 
from certain stars has not been thought too difficult. 
Mr. Stone, making use of the powers of the great 
equatorial of the Greenwich Observatory, and inge- 
niously overcoming the numerous difficulties which 
exist in a research of such exceeding delicacy, has 
arrived at the conclusion that Arcturus sends us about 
as much heat as would be received from a three-inch 
cube full of boiling water, and placed at a distance of 
three hundred and eighty-three yards. Vega, which 
shines, according to Sir J. Herschel, with about two- 
thirds the light of Arcturus, gives out about the same 
proportionate amount of heat.* But in other in- 
stances the heat-giving power of a star has not been 
found proportional to the amount of light it emits. 

The variation of many fixed stars in lustre at once 
forms a new bond of association between the stars and 

* Although these results cannot yet be regarded as numerically ex- 
act, it may be interesting to consider the amount of heat given out by 
Arcturus in relation to the light sent us by this star, the more so as this 
star seems (from the nature of its spectrum) to resemble the sun very 
closely in constitution. 

The light sent to us by Arcturus is equal to about three-fourths of 
that supplied by Alpha Centauri, or about ^rnTnr.WuroTnjth P ar * of the 
light we receive from the sun. Now, Mr. Stone estimates the direct 
heating effect of Arcturus at 0°. 00,000,12'? Fahrenheit, making due al- 
lowance for the effect of the object-glass in concentrating and absorbing 
the heat. It will be seen at once that, according to this estimate, the 
heating power of Arcturus bears a very much greater proportion to 
that of the sun than the respective light-giving powers of these lu- 
minaries bear to each other. This seems to throw some doubt on the 
correctness of the estimate, eithei of the light-giving or of the heat-giv- 
ing power of the star. 






OTHER SUNS THAN OURS. 255 

the sun — which we have seen to he in reality a vari- 
able star — and suggests interesting inquiries as to the 
existence of variation in the emission of heat. Some 
of the stellar variations of light are so much more 
marked than those noticed in the case of our own sun 
that we can scarcely conceive how creatures, resem- 
bling any with which we are acquainted, could endure 
the effects of corresponding important variations of 
heat; nay, in some instances we seem compelled to 
withhold our belief in the existence of habitable sys- 
tems around certain fixed stars. The star Eta Argus, 
for example, which sometimes blazes out with a light 
surpassing that of any of the stars in the northern 
hemisphere, while at other times it falls to the sixth 
magnitude, can hardly be regarded as fit to be the 
centre of a system of worlds. I pass over such varia- 
ble stars as the one which recently blazed out in the 
Northern Crown, because in a case of this sort the star 
may be regarded as really a small orb, and its sudden 
lustre as due to some exceptional occurrence, leading 
(as the spectrum of the star seemed to show) to a tem- 
porary conflagration. But Eta Argus and Mira Ceti 
seem to belong to a different category altogether, since 
it is probable as respects the former, and certain as re- 
spects the latter, that their appearance as stars of the 
leading magnitudes is not accidental, but part of a 
systematic series of changes. 

It remains only to be mentioned that, besides light 
and heat, the stars emit actinic rays. This is proved 
decisively by the fact that the stars can be made to 
photograph themselves. It has been found, however, 



256 OTHER WORLDS THAN OURS. 

that the actinic power of a star, like its heat-giving 
power, is not by any means proportional to the star's 
light. So that in this respect, as in the material con- 
stitution of the stars, we find specific varieties even 
amid those very features which indicate most strik- 
ingly the general resemblance which exists between 
the suns constituting the sidereal system, 

To sum up what we have learned so far from the 
study of the starry heavens — we see that, besides our 
sun, there are myriads of other suns in the immensity 
of space ; that these suns are large and massive bodies, 
capable of swaying by their attraction systems of 
worlds as important as those which circle around the 
sun ; that these suns are formed of elements similar to 
those which constitute our own sun, so that the worlds 
which circle round them may be regarded as in all 
probability similar in constitution to this earth ; and 
that from those suns all the forms of force which we 
know to be necessary to the existence of organized 
beings on our earth are abundantly emitted. Is it 
not reasonable to conclude that these suns have not 
been made in vain ? If thoughtful men have reasoned 
rightly in supposing that the light and heat poured out 
by the sun upon the planets which circle around him 
are not wasted — in the case of all the planets except 
our small earth — by being shed where no forms of life 
can profit by those abundant supplies, surely the argu- 
ment is a million-fold stronger in the case of the fixed 
stars. Though here we cannot, as in the case of the 
solar system, actually see the worlds about which we 
speculate, yet the mind presents them clearly before 



OTHER SUNS THAN OURS. 2 tf 

as, various in size, various in structure, infinitely vari- 
ous in their physical condition and habitudes, bu 
alike in this, that each is peopled by creatures per- 
fectly adapted to the circumstances surrounding them, 
and that each exhibits in the clearest and most strik- 
ing manner the wisdom and beneficence of the Al- 
mighty. 



17 



CHAPTEK XL 

OF MINOR STARS, AND OF THE DISTRIBUTION OF STARS 
IN SPACE. 

It has been so long a received opinion that a gen- 
eral uniformity of magnitude and distribution charac- 
terizes the stellar system that it is with some diffi- 
dence I venture to express a different view. And here 
let me not be misunderstood. I am fully sensible 
that it is only in certain popular treatises of astron- 
omy that a belief in any thing like a real uniformity of 
structure in the sidereal system is attributed to astron- 
omers of authority. It is not any such imaginary 
theory that I have now to deal with, however, but 
with opinions which have found a place in the works 
of astronomers from whom I very unwillingly differ. 

I propose to exhibit the reasons which have led me 
to believe that, so far from knowing the real figure of 
the sidereal system, astronomers have not been able to 
penetrate to its limits in any direction ; that leading 
stars, such as those discussed in the preceding chapter, 
are distributed throughout space to the very farthest 
limits and beyond the very farthest limits that our 
most powerful telescopes can attain to ; that the stars 






MINOR STAES. 2 59 

are arranged in groups and clustering aggregations, in 
streams and whorls and spirals, in a manner altogether 
too complex for us to hope to interpret ; and that in 
these aggregations stars of all degrees of real magni- 
tude are mixed up, from suns as large as Sirius down 
to orbs which may be smaller than any of the primary 
planets of the solar system. 

Now let us consider step by step the evidence we 
have on these points. 

We know, from the existence of double, triple, and 
multiple stars, in which the components are often 
very unequal in splendor, that combinations of stars 
exist in which one or two may be suns like our own, 
while the rest, or some of the rest, are relatively mi- 
nute. This, however, has of course long been known ; 
and it is only as a preliminary step in the investigation 
that I here advance so trite an instance. 

Next let us consider such star-clusters as contain 
orbs of the eighth or ninth magnitude, besides a mul- 
titude of minute stars. These clusters must of course 
be regarded as lying within the sidereal system, since 
no external galaxies could reasonably be supposed to 
contain orbs so infinitely transcending even Sirius in 
magnitude as to shine from beyond the enormous gap 
separating us from such galaxies with a light exceed- 
ing that derived from many stars within the sidereal 
system. Now, regarding these clusters as forming 
part and parcel of the sidereal system, we find in the 
existence of multitudes of minute orbs within their 
range a proof that diversity of magnitude in schemes 
of associated stars is to be regarded as a feature of 



2 6o OTHER WORLDS THAN OURS. 

certain parts, at any rate, of our galaxy ; and we shall 
therefore be the less surprised if we should find rea- 
son for believing that it is a characteristic peculiarity 
of the galactic system. 

Now, with regard to the nebulae (resolvable and ir- 
resolvable), and their claim to be regarded as external 
galaxies, I shall have much to say farther on ; but I 
may remark, in passing, that we have precisely the 
same reasons for believing that many of these objects 
lie within the range of the solar system as have been 
already considered in the case of star-clusters. Their 
component stars, to be visible at all, must fall within 
the range of distance which astronomers have assigned 
to the boundaries of the galaxy, since some stars even 
within that range cease to be separately visible in the 
most powerful telescopes man has yet constructed. So 
that when in these objects we see a few or many dis- 
tinct stars, and a mass of nebulous light which we 
judge to proceed from an indefinitely large number 
of minute stars, we again have very decided evidence 
of the fact that in one and the same region of the side- 
real system there may exist leading stars (so to speak) 
and innumerable stars relatively minute. 

With considerations such as these (and I might add 
many others) to guide us, let us proceed to consider 
the teachings of the Milky Way itself, that we may 
see whether that wonderful zone indeed represents, as 
has been thought, the sidereal system itself, or only 
an aggregation of minute orbs altogether insignificant, 
separately, in comparison with our sun or Sirius. 
Aldebaran or Betelgeux, Yega or Arcturus. 



MINOR STARS. 261 

The star-gauging of Sir "W. Herschel, interpreted 
according to his hypothesis of stellar distribution, 
pointed to an extension of the Milky TTay laterally to 
a distance exceeding some eighty times that which 
separates us from the first-magnitude stars. So that, 
regarding sixth-magnitude stars as on the average 
about ten times as far from us as those of the first 
magnitude (the usual estimate), we see that the outer- 
most parts of the galaxy must lie (according to Sir 
W. Herschel's theory) about eight times as far from 
us as the sphere of the sixth-magnitude stars. Xow, 
Sir John Herschel was led by his observations of the 
southern heavens to so far modify his father's theory 
as to describe the Milky Way as probably shaped like 
a flat ring, the stars down to the tenth magnitude 
being in a sense dissociated from the ring, while he 
regarded the probable distance of the outermost limits 
of the ring as seven hundred and fifty times instead 
of but eighty times the mean distance of the first -mag- 
nitude stars. This difference of opinion, it may be 
remarked, though obviously not surprising when we 
consider the enormous difficulty of the problem pre- 
sented by the sidereal system, is yet sufficient to indi- 
cate the probability that an important error has been 
made in the hypothesis which underlies the accepted 
theories respecting the galaxy. But, be this as it may. 
in regarding the Milky Way as shaped like a flat ring 
(cloven through one half of its circumference) whose 
medial section resembles generally the space between 
the dark concentric circles in the accompanying fig- 
ure (in which SB equals eight times SA), I have not 



262 



OTHER WORLDS THAN OURS. 



adopted a structure which exaggerates the difficulties 
presented by the disk or ring theory of the Milky Way. 




Fig. 2.— The Galactic Cloven Flat Eing (plan). 

The cross-section would be somewhat as shown in 
Fig. 3. 

Now, accepting this modified figure, as better ac- 
cording with the results of star-gauging than Sir W. 




Fig. 3.— The Galactic Cloven Flat Eing (section). 



HerschePs theory that the Milky Way forms a cloven 
disk, let us consider whether any peculiarities of the 



MINOR STARS. 263 

Milky Way seem to oppose themselves to this inter- 
pretation of its structure. 

In the first place, then, there is a gap or rift ex- 
tending right across the single part of the Milky Way 
in the constellation Argo ; so that we must conceive 
that from S toward 1, in Fig. 2, the flat ring is broken 
through by some such rift as is indicated by the broken 
lines in that direction. Next there is, in the constella- 
tion Crux, a pear-shaped vacuity of considerable size, 
and bounded by well-defined edges ; so that we must 
conceive that from S toward 2 (Fig. 2) the flat ring 
is tunnelled through by some such passage as is indi- 
cated by the dotted lines in that direction. A similar 
tunnelling, but of different cross-section, must exist in 
direction S 3 (as shown by the dotted lines) to account 
for the dark gap in the constellation Cygnus. Next, 
where the Milky Way is double, a large portion of one 
branch is discontinuous, so that the upper part of the 
double portion of the ring in Fig. 2 must be supposed 
removed between the broken lines from S to 4 and 5. 
Over the so-called double stream there are in places 
strange convolutions, in others numerous branching 
and interlacing streams, whose complexity indeed de- 
fies description ; so that the portion 3 B 2 of the ring 
must be supposed corrugated in the strangest way, 
and further to throw out plane and curved sheets of 
stars presented tangentially toward S. Lastly, the 
single portion of the Milky Way is very faint indeed 
toward 6, so that here we must conceive its figure 
trenched in upon in the way indicated by the dot-and 
peck line. 



264 OTHER WORLDS THAN OURS. 

Thus, even without considering a multitude of mi- 
nuter peculiarities of structure, we are led to the con- 
clusion that the Milky Way, judged according to the 




Fig. 4. — The Galactic Flat King, modified in accordance with the 
observed peculiarities of the Milky Way. 



fundamental hypothesis of Sir W. Iierschel, has some 
such shape as I have endeavored to exhibit in the ac- 
companying figure. Although I have not indicated 
here the corrugations of the ring, nor a tithe of the 
various overlapping layers which would be required to 
account for the appearance of the Milky Way between 
Centaurus and Ophiuchus, yet the deduced figure is 
by no means inviting in its simplicity. It is, however, 
absolutely certain that the sidereal system, as far as its 
more densely aggregated star-regions are concerned, 
has some such figure as this, it we are to accept the 
principle of Sir "W". Herschel's star-gaugings. 

Now, in turning our thoughts to the recognition of 
a more simple explanation of observed appearances, it 
will be well that we should consider some peculiarities 



MINOR STABS. 265 

of the Milky Way which we have not yet attended to. 
In the first place, I would invite attention to a pecu- 
liarity observed by Sir John Herschel in different 
parts of the galaxy — the fact, namely, that in places 
the edge of the Milky Way is quite sharply defined. 
One half of a telescopic field of view may be quite 
clear of stars, or show only a few straggling orbs, while 
the other half presents what has been called a " Milky 
Way field " — that is, a region profusely sprinkled with 
stars, the boundary between the two portions being 
well defined. "When we see that a cluster of objects 
presents a well-defined edge, what conclusion do we 
draw as to the position of the object? Is it not in 
such a case absolutely certain that the distance of the 
cluster enormously exceeds the distance between its 
component parts — or, in other words, that the observer 
is far outside the cluster? Many instances will at 
once suggest themselves to the reader in illustration 
of this remark. 

We conclude, then, that these portions of the Milky 
Way, at any rate, whether they be regarded as projec- 
tions or nodules, are definite clustering aggregations 
very far removed from us. Other parts of the Milky 
Way may also be removed bodily, so to speak, to 
enormous distances, because a cluster which has not 
a definite edge may be as far removed as one which 
has ; but certainly those portions are. 

Isext let us consider what opinion we may found 
on the existence of dark regions in the Milky Way ; 
and here I refer not merely to such large and obvious 
vacuities as the coal-sack in Crux or the oval opening 



266 OTHER WORLDS THAN OURS. 

in Cygnus, but also to small openings, in which, though 
they occur even in rich regions of the Milky Way, 
there is not, according to Sir W. HerschePs descrip- 
tion, even a telescopic star to be seen. 

Judged apart from preconceived opinions, such 
openings as these, according to all laws of probability, 
indicate that the portion of the Milky Way in which 
they occur has not a very great lateral extension. To 
return for a moment to Fig. 2, it will be seen at once 
that an aperture extending laterally through a star- 
system so shaped must have a particular direction and 
be perfectly straight in order to be visible to observers 
placed, as we are supposed to be, in the central open- 
ing. It is altogether improbable that one such open- 
ing should exist by accident, and absolutely impos- 
sible that many should.* We are forced therefore to 
infer that, instead of the enormous lateral extension 
assigned to the Milky Way, the galaxy has in thes8 
places certainly, and elsewhere probably, a lateral ex- 
tension not greatly exceeding its depth. 

It is further to be noted that the lucid stars over 
that zone of the heavens which is occupied by the 
galaxy show a very decided preference for the parts 
of that zone which are actually traversed by the Milky 
Way. For instance, we find no stars above the fifth 
magnitude, and very few of these, in the Coal-sacks, or 

* Sir John Herschel has distinctly indicated this inference, as he has 
many other matters which make strongly against the received theory of 
the sidereal system. Nor is he unconscious of their bearing. Appar- 
ently unwilling at present to press them to their full extent, he is com- 
monly satisfied by noting that they do not seem to accord with views he 
has elsewhere dwelt upon. 



MINOR STARS. 



267 



in the rift which crosses the Milky Way in Argo, or, 
again, in the space which lies between the two branches 
where the Milky "Way is donble. If this is an accident, 
it is a Yery extraordinary one, especially when it is re- 
membered that the region where it occnrs is the very 
part of the heavens where stars of all magnitudes may 
be expected to be most profusely distributed ; that the 
spaces thus left vacant form no inconsiderable aliquot 
part of that zone ; and that, according to the accepted 
theory, there is no reason for expecting any peculiarity 
of the sort. 

Thus, again, setting aside preconceived opinions, 
and judging only according to the evidence, we seem 
led to regard the coincidence as not accidental,, but as 
indicating that there really is a very close association 
between the bright stars and those small stars form- 
ing the milky light, which, according to the accepted 
theory, would lie so many times farther from us.* 

Now, if we have not been mistaken so far, it is very 
clear what views we are to form. If the Milky Way 
is to he, first, a clustering aggregation separated from 
us by an interval comparatively clear of small stars ; 
secondly, so shaped that the cross-section of the stream 
is everywhere not far from a roughly circular figure ; 
and, thirdly, associated very closely with the bright 
stars seen in the same field of view, then must its 

* I may add that, in drawing the maps for my new star-atlas, I have 
been very much surprised to find how in many cases the position, nay 
the very shape, of the Milky Way is indicated by the iucid stars which 
fall on its zone. Although my own views had led me to look for a pe- 
culiarity of the sort, it has been much more striking in its character than 
I had expected. 



2 68 OTHER WORLDS THAN OURS. 

structure be somewhat as shown in Fig. 5, in which 
the disks represent lucid stars (very much exagger- 
ated of course in size), while the fine dotting represents 




Fig. 5. — The Milky Way regarded as a Spiral. 

the spiral of relatively minute stars, clustering along 
the spiral group of leading stars. It will be seen at 
once how, to an observer placed at S, the various fea- 
tures of the Milky Way can be accounted for by this 
figure. Toward a would lie the gap in Argo ; toward 
b two branches, one faint, and in part evanescent 
through enormity of distance, the other forming the 
brightest part of the spiral ; toward d the projection in 
Cepheus ; toward e the faint part of the Milky Way in 
Gemini and Monoceros. The Coal-sacks would be 
simply accounted for by conceiving that branches seen 
toward the same general direction, but at different 
distances, do not lie in the same general plane, and so 
may appear to interlace upon the heavens. We are 
not only justified in supposing this, but forced to do 



MINOR STARS. 269 

bo by the way in which the stream of milky light is 
observed to meander on its course athwart the heavens. 
The branching extensions serve very well to account 
for the appearance of the Milky Way between Centau- 
rns and Ophiuchus, where the interlacing branches and 
the strange convolutions and clustering aggregations 
described by Sir John Herschel are chiefly gathered. 

I would not have it understood, however, that I at 
all insist on the general shape of the spiral shown in 
Fig. 5. On the contrary, that curve is only one out of 
several which might fairly account for the observed 
appearance of the Milky Way ; and I have often felt 
inclined to doubt whether a single spiral of this sort 
be in reality the best way of accounting for the ob- 
served appearance of the galactic zone. What I do 
insist upon as most obviously forced upon us by the 
evidence is, that (1) the apparent streams formed by 
the Milky Way upon the heavens indicate the exist- 
ence of real streams in space ; and (2) that the lucid 
stars seen on the stream are really associated with the 
telescopic stars which form, so to speak, the body of 
the stream. Whether that stream form a single spiral 
or several, or whether, instead of spirals, there may not 
he a number of closed rings of small stars, placed at 
different distances from us, and lying in all directions 
round the medial plane of the galaxy, but m,ore or less 
tilted to that plane (the sun not lying within any one 
of the rings), are questions which can only be resolved 
by the systematic scrutiny of this wonderful zone. 

The chief points to be noticed among the considera- 
tions flowing from these general views are these : 



j» 7 o OTHER WORLDS THAN OURS. 

In the first place, the only marked difference be- 
tween the stars of the leading magnitudes (say the 
first ten) lying in the galactic zone, and those lying 
without it, consists in the fact that the former are as- 
sociated with countless multitudes of smaller stars, 
while the latter appear not to have such attendants, or 
not so many of them. We shall see presently that the 
extra-galactic stars are associated, and in a very in- 
timate manner, with groups of very minute stars — of 
stars so minute indeed as not to be separately discern- 
ible — so that astronomers have been led to regard such 
groups as external galaxies. But, except in one region, 
we do not find outside the galactic zone any appear- 
ances reminding us of the aspect of the Milky Way 
itself. In that region lie the two Magellanic Clouds, 
resembling the Milky Way in their general appearance, 
but seen when placed under telescopic scrutiny to differ 
from it in this, that among the minute stars which 
cause the milky light are numbers of nebulae, of classes 
not found commonly, if at all, in the galactic zone. 

In the second place, we must conclude that un- 
counted millions of stars exist which are very minute 
indeed in comparison with those which we have been 
led to regard as suns. That these relatively minute 
orbs may be absolutely large — far larger, for instance, 
than our own earth — may indeed be accepted as cer- 
tain. But it is difficult to believe that they subserve 
purposes similar to those of our own sun. One cannot 
but see that orbs such as these would not have that 
permanence Df character, as sources of heat-supply, 
which would seem to be necessary in the case of area\. 



MINOR STARS. 271 

dun. We know, indeed, that among the small stars 
of the Milky Way there is a proneness to irregular 
variation which is not recognized, or is altogether ex- 
ceptional, among the lucid stars. In the neighbor- 
hood of the Milky Way, with scarcely an exception, 
those temporary stars have blazed out which have 
formed a subject of such perplexity to the thoughtful 
astronomer. Under what conditions the small orbs in 
the Milky Way actually exist, whether clusters of them 
will eventually segregate from their neighbors to form 
suns, or whether, after long voyaging in spiral and con- 
torted paths under the varying influences of the attrac- 
tions of leading stars, these minute orbs will, for the 
most part, be forced to settle down as attendants round 
the major ones, it is as yet altogether impossible to 
judge. It may be that they bear the same sort of re- 
lation to the leading stars that certain cometic and 
metoric families, referred to in Chapter IX., bear to 
the major planets of the solar system, not being in any 
case absolutely dependent on any large star, but jet 
returning in cycles which must be measured by mill- 
ions of eons, to temporary dependence on one sun 
after another, until in the course of time, under the 
action of processes somewhat resembling those I have 
conceived to take place in the formation of the solar 
system, the conditions under which they move will 
have become so far altered as to lead to the breaking 
up of the Milky Way into distinct systems. Indeed, 
as Sir William Herschel was led by other considera- 
tions long since to point out, there are signs in parts 
of the Milky Way which woujd seem to indicate that 



ijz OTHER WORLDS THAN OURS. 

several such systems have already reached an advanced 
stage of development. 

But perhaps the most important conclusion de- 
ducible from the circumstances I have dwelt upon 
(assuming my interpretation of them to be in the main 
correct) is this, that we can no longer suppose we have 
in any direction pierced to the limits of the sidereal 
system. So long as a general approach to uniformity 
of distribution was understood to prevail within that 
system, there was a ready means of determining when 
the telescopist had reached in any given direction the 
limits of the system. To use the words of Prof. 
Nichol, " When an eye is directed toward a prolonged 
bed of stars, there is no reason to fancy that it has 
reached the termination of that stratum so long as 
there appears, behind the luminaries which are indi- 
vidually seen, any milky or nebulous light ; such light 
probably arising always from the blended rays of re- 
moter masses. But, if, after struggling long with a 
nebulous ground, we obtain a telescope that gives us 
additional light with a perfectly hlack shy, we then 
have every reason the circumstances can furnish on be- 
half of the supposition that at length we have pierced 
through the stratum, a probability, indeed, which can 
be converted into certainty in only one way — viz., 
when no increase of orbs follows on the application of 
a still larger instrument." Sir John Herschel has ex- 
pressed a similar view, and there can, indeed, be no 
doubt that, adopting the fundamental hypothesis on 
which accepted views are founded, the test above de* 
scribed is an absolutely certain one. 



MINOR STARS. 273 

But, if, instead of penetrating farther and farther 
hue- space when "struggling long with a nebulous 
ground " (to use Prof. Mchol's striking but somewhat 
incorrect expression), we have in reality only beeD 
searching with more and more minuteness within a 
definite cluster or stream of stars, we can no longer 
come to the conclusion he has insisted upon. We 
have reached the limits of minuteness which the stars 
of the cluster or stream attain to ; we have learned per- 
haps all that we can learn about that cluster or stream ; 
but we can no more be said to have reached the limits 
of the sidereal system in that direction than we can 
be said to have reached the outermost bounds of the 
universe in the direction of the cluster in Hercules, 
when that magnificent object has been thoroughly re- 
solved with the telescope. 

Here, then, if I have seemed to narrow the limits 
of the sidereal scheme by bringing the star-myriads 
of the Milky Way, which had been regarded as many 
times farther from us than the lucid stars, into direct 
association with these luminaries, I make amends by 
pointing out that in all probability the limits of the 
sidereal system lie far beyond the range of the most 
powerful telescopes man has yet constructed. In fact, 
there is here a somewhat singular interchange of po- 
sition between the new and the accepted theories. 
According to the views usually accepted, the small 
stars in the Milky Way are really as large, on the av- 
erage, as the lucid stars, whereas, according to my 
views, they are relatively minute. But, according tc 
tiie accepted theories, the scattered stars of very low 
18 



274 



OTHER WORLDS THAN OURS. 



magnitudes in the extra-galactic heavens must be re- 
garded as relatively minute, since it has been rendered 
certain, according to those theories, that the limits of 
the sidereal system are relatively close in this direc- 
tion, and we cannot suppose these stars to lie beyond 
those limits (as they must do, if really large). Now, 
according to my views, there is nothing to prevent 
these minute stars from including among their num- 
ber orbs as vast as Sirius, or many times vaster. 
JSTay, even within the galactic zone itself there are 
stars to which my theory gives as noble proportions as 
the accepted views. For, in the southern Coal-sack, 
there are minute telescopic stars, as Sir John Herschel 
tells us, and these orbs, according to the accepted 
views, must be regarded as belonging to the galactic 
circle, though inexplicably segregated from their fel- 
lows, According to the views I have been led to 
form, many of these telescopic stars must be regarded 
as suns lying far beyond the galactic spiral, or perhaps 
associated with outer whorls of this spiral which no 
telescope made by man can ever reveal to us. 

And this leads me to consider two phenomena 
which are altogether inexplicable, I conceive, on any 
theory except mine. 

The first is the existence of excessively faint 
streams of light — star-streams doubtless, though the 
components are not separately visible — in certain re- 
gions of the heavens. Sir John Herschel, who de- 
tected this strange phenomenon, speaks of the streams 
as so very faint that the idea of illusion has contin- 
ually arisen subsequently ; yet he dwells far too 



MINOR STARS. 275 

clearly on the characteristics of the phenomenon for 
any doubt to remain as to its reality. The faintest 
possible stippling of the field of view — the minnte 
points of light being obviously there, though it was im- 
oossible to see them individually — a mottling which 
moved with the stars as he moved the tube to and fro, 
such are the terms in which Sir John Herschel speaks 
of this interesting phenomenon. 

Now, no doubt whatever can exist that, if these 
faint streams really belong to the sidereal system, they 
are left altogether unaccounted for by the ordinary 
views respecting the structure of that system. There 
is no continuity between the stars composing them 
and even the minutest telescopic stars visible in the 
same general direction ; so that a vast void must sepa- 
rate them from the outermost of those telescopic stars. 
According to my theory, they simply belong to out- 
lying whorls of the spiral galaxy, and the telescopic 
stars seen upon them bear the same relation to them 
that the lucid stars bear to the Milky Way. 

The second point is perhaps even more striking. 
In certain directions Sir John Herschel recognized the 
existence of two or more distinctly-marked classes of 
stars, as though, he says, definite sets of stars, sepa- 
rated by comparatively void intervals, lay in those 
directions. It is clear that this association of the 
stars into sets is as distinctly opposed to the views 
ordinarily accepted as it is obviously an arrangement 
to be expected according to my theory of the constitu- 
tion of the sidereal system. 

Quite early in my consideration of the subject I am 



276 OTHER WORLDS THAN OURS. 

now upon, the idea suggested itself to me that in the 
proper motions of the stars we have a means of form- 
ing an estimate of the distances of these orbs; and, 
further, of detecting any laws associating them to 
gether, whether into streams or clusters ; and that the 
evidence thus, obtained was likely to be in many re- 
spects more trustworthy than that afforded by the 
apparent magnitudes of the stars. Two processes of 
inquiry suggested themselves. The first consisted in 
a careful comparison of the mean motions of stars of 
different apparent size, in order to determine whether, 
on the average, small stars are so far off that we can 
look upon them as in reality no smaller on the average 
than those which appear larger. The second consist- 
ed in charting down the proper motions, so as to de- 
tect any signs of star-drift which might haply appear 
in different parts of the heavens. I confess that I had 
not by any means expected results so strikingly con- 
firmatory of my views as those I actually obtained. 

The first method of inquiry, instead of giving an 
average amount of proper motion to the smaller stars 
somewhat, or perhaps even considerably, greater than 
was to be expected, according to the theory which sets 
these stars at an enormous distance, actually gave 
them a mean motion equal to that of stars of the first 
three magnitudes. It became evident, then, that not 
only are small stars (I am here speaking of stars visi- 
ble to the naked eye) mixed up as I had thought with 
bright stars visible in the same general direction, but 
that distance is less available to explain the smallness 
of the stars even than I had supposed. I had thought 



MINOR STARS. 277 

that certainly a large proportion of the small stars 
must in reality be very far from ns ; but it appeared 
that the proportion of stars whose smallness is so to be 
accounted for is in reality exceedingly minute. There 
must therefore be myriads of really small stars for 
every leading orb. 

The second method of research led to the strange 
result that in many parts of the heavens a community 
of motion can be recognized, among star-groups far 
larger in extent than I had expected to find thus drift- 
ing through space. Knowing that, whatever view we 
form of the sidereal universe, we must yet recognize 
the fact that in every direction stars at very different 
distances must be visible, I had not hoped to find over 
any large region of space the traces of a community 
of motion. Xor even in small regions had I hoped to 
recognize very decided traces of star-drift, because I 
was conscious that, even with three or four stars really 
forming a drifting group, there would nearly always 
be found three or four others, either much farther off 
or much nearer, and altogether dissociated from the 
drifting set. Indeed, I imagined, when I began the 
inquiry, that the most remarkable instance of star- 
drift in the heavens was that detected (though dif- 
ferently explained) by Baron Madler in the constella- 
tion Taurus. 

I found, however, that in other regions a far more 
obvious tendency to drift can be recognized. Perhaps 
the most remarkable instance of all is that illustrated 
in the accompanying plate. This picture represents 
the motions in the constellations Cancer and Gemini. 



278 OTHER WORLDS THAN OURS, 









^ 




s 



/ I 



Q 



It will be noticed tliat though here and there stars ap- 
parently not belonging to the system appear in the 
same range of view, yet the star-drift is unmistakable. 
The general parallelism of motion is very striking; 
and the difference in the amount of motion observed 
in different stars is only what was to be expected in a 
star-group whose range in distance, if equivalent to its 



MIX OR STARS. 2 ?g 

lateral extent, must be such as fully to account for the 
range in the amount of apparent motion. 

Fig. 6 exhibits one out of many parts of the heav- 
ens in which different sets of stars are observed to be 
drifting in different ways. 

It will be seen that here there are three sets — those 
included in the space a, those in space h, and those 
left unenclosed, which are very obviously drifting, 






P /3 



Fia. 6. — Observed Proper Motions of Stars in Ursa Major and 
Neighborhood. 



each in its special direction. The stars within the 
space h are 0, y, 8, e, and f, of the Greater Bear, with 
three smaller stars. Their drift is, I think, most sig- 
nificant. If in truth the parallelism and equality of 



2 8o OTHER WORLDS THAN OURS. 

motion are to be regarded as accidental, the coinci- 
dence is one of a most remarkable character. But 
such an interpretation can hardly be looked upon as 
admissible, when we remember that the peculiarity is 
only one of a series of instances, some of which are 
scarcely less striking. One of these is presented in 
the accompanying figure in which the proper motions 
in the stars a, ft, and <y, Arietis, and four other stars 
in the neighborhood, are exhibited.* 

Here /3 and 7 may be regarded as drifting with a, 
but haying a motion of their own in addition, suffi- 
cing to account for the want of strict parallelism be- 
tween their apparent motion and that of a. The 
other stars seem obviously to belong to the same sys- 
tem. 

06 

Fig. 7.— Observed Proper Motions of Stars in Head of Aries. 

I am led, by the facts which have here been briefly 
considered, rather to urge those who have time and 
inclination to inquire carefully into the minuter de- 
tails of the sidereal heavens than to insist on any 

* In all these figures the proper motion indicated by the length of 
the arrow attached to a star corresponds to the star's motion in thirty- 
six thousand years. 



MIX OR STARS. 2 8l 

views of my own. While I recognize the wisdom and 
necessity of that course which the Herschels adopted 
in taking a wide view of the sidereal system, and in 
dealing rather with general results than with special 
peculiarities, I think the time has come when another 
course is possible and advisable. The Herschels hav- 
ing surveyed the field of heaven, it behooves us now 
to go over it with a close and searching scrutiny. To 
consider averages now is to level the scarcely percep- 
tible undulations in our field of research, as well as its 
better-marked ridges or depressions ; whereas we re- 
quire, on the contrary, to exaggerate the variations of 
level, so that we may determine with more certainty 
what are the peculiarities presented by that most in- 
teresting field to man's contemplation. Or, to change 
the illustration, and to quote the words of the greatest 
living master of that kind of research which I have 
been advocating, " We must not be deterred from 
dwelling consecutively and closely on these specula- 
tive views by any idea of their hopelessness which the 
objectors against ' paper astronomy ' may entertain, 
or by the real slenderness of the material threads out 
of which any connected theory of the universe has (at 
present) to be woven. ' Hypotheses jingo ' in this 
stage of our knowledge is quite as good a motto as 
ISTewton's ^Non jingo ' — provided always they be not 
hypotheses as to modes of physical action for which 
experience gives no warrant." * 

* From a letter addressed by Sir J. Herschel to the present writer 
August 1 1869. 



CHAPTER XII. 

THE NEBULAE I ARE THEY EXTEKNAL GALAXIES ? 

In the last chapter I have indicated reasons fur 
believing that the sidereal system extends far beyond 
the range of the most powerful telescopes man has yet 
been able to construct. It need hardly be said that, 
supposing this view to be correct, we cannot possibly 
see any external galaxies, unless they surpass our own 
many thousands of times in richness and splendor. 
Every analogy that we have for our guidance points 
to the conclusion that, if our galaxy have limits, and 
there exist in space other galaxies, then those outer 
systems must be separated from ours by spaces ex- 
ceeding the dimensions of the several galaxies many 
thousand or many million fold in extent. We know 
that the distances separating the satellites from their 
primaries exceed in an enormous ratio the dimensions 
of the satellites. The distances separating the planets 
from each other exceed in an enormous ratio the di- 
mensions of the planets. The distances separating 
our solar system from others enormously exceed the 
dimensions of the various solar systems. And we may 
conclude that in all probability the distances separat- 



TEE NEBULA. 



283 



mg our sidereal system from other similar systems in 
space must exceed in an enormous ratio the dimen- 
sions of our galaxy, and of all other such systems. 

That the sidereal system has limits I do not doubt. 
Of course it may be coextensive with space that is 
absolutely infinite in extent ; but we have no reason 
for believing that, in rising step by step, from system 
to system, until we have reached the highest class of 
system known to us, we have reached the real summit 
of that perhaps altogether limitless range of steps. 
We know, indeed, that if light do not suffer extinction 
in traversing space (and we have as yet no evidence 
that it does), the extent of the sidereal system must be 
limited, since otherwise the whole of the starlit sky 
should shine with the brilliancy of sunlight.* And we 

* This is, perhaps, obvious ; but, if not, the following proof may be 
accepted : Let the whole of space be conceived divided into spherical 
shells, having our earth at their centre, the thickness of each shell being 
t. Then taking two shells, one at a distance r, the other at a distance 
r' (both r and r' much greater than t), we see that the number of stars 
in these shells will be proportional to r 2 t and r' 2 r respectively ; that is, 
will be independent of the thickness of the shell and vary as the square 
of its radius. (Here I am not concerned with those departures from uni- 
formity which I have considered in the last chapter, because I suppose 
each shell large enough to include within it all varieties of distribution 
and aggregation. This applies, also, to what follows.) Now, the average 
apparent size of the stars of one shell will be to the average apparent 
size of stars in the other in the inverse proportion of the respective 
radii of the shells, the intrinsic brightness of the light received from the 
stars of each set being equal. Thus the total amount of light from the 
ctars of one shell is to the total amount of light from stars in the other, 

asr'rx-j: r' 3 t x -^=1 : 1. Hence, supposing the amount of light 

received from one shell to be -yth part of that which would be received 
if the whole celestial sphere were as bright as the sun's, that is as a 



284 OTHER WORLDS THAN OURS. 

may carry this argument even further. For, though 
the sidereal system should be limited, but other sys- 
tems similar to it spread throughout the infinity of 
space, there would still result this ineffable blaze of 
light, surpassing the light of day as greatly as the vault 
of heaven surpasses the disk of the sun. And this 
again would be true, though this system of systems 
were limited in extent, but surrounded by similar sys- 
tems of systems in the infinity of space. And so on, 
let the order of systems which finally becomes infinite 
in number be what it may. There is only one way to 
escape from this limitless series of system-orders — that 
is, by accepting as true the hypothesis that light suffers 
extinction as it voyages through space. But it is worth 
noticing, when we are actually dealing with the infini- 
ty of space, and when, therefore, limitless conceptions 
are not paradoxical, but in reality as available for our 
purposes as finite conceptions would be, that if we do 
adopt the belief in an infinite succession of orders of 
systems, that is, first satellite-systems, then planetary 
systems, then star-systems, then systems of star-sys- 
tems, then systems of systems of star-systems, and so 

star's disk — k being inconceivably large, the amount received from the 
other is also 7 th of this amount, and the total from all the shells must, 

therefore, be -r + £ + X + %. to infinity. 

Now, by taking k terms of this series (or k shells out of our infinite 
series of shells), we should get unity, that is, the whole heavens lighted 
up with starlight or sunlight. There would be a proportion of stars in 
the same visual line and so hiding each other ; but, since we can take 
2 k, 3 k, or infinity times k if need be, there can be no doubt the whole 
heavens would be lighted up with solar brightness. 



THE NEBULAE. 



285 



on to infinity, and if we accept as true of this infinite 
series what we know to be true of the part within our 
ken, viz., that the distance between the components 
forming any system is indefinitely great compared with 
the dimensions of those components, we no longer have 
as a conclusion that the whole heavens should be 
lighted up with stellar (that is with solar) splendor ; 
even though, in this view of the subject, there are in 
reality an infinite number of stars, just as in the view 
according to which the sidereal system extends with- 
out interruption to infinity.* 

But whether we adopt this or any other view of 
the way in which external systems are arranged, this 
at any rate is certain, that if the stars at the outer 

* It is clear that we no longer get, as in the previous note, a series 
of equal small terms. If we take our infinite series of shells as before, 

we get for the sidereal system n times - where n is finite and therefore 

_ finite. We must indeed assume - to be small, and so of other similar 
k k 

ratios presently to be dealt with. With respect to the system of systems 
we have these considerations to guide us, — any of the spherical shells 
within this system must supply to our skies an amount of light indefi- 
nitely less than one of the shells within the sidereal system itself, say 

_ th part only, k' indefinitely large ; but the number of shells falling 

V 

within that system is very much greater, say n' times as great where «' 

is finite. Therefore we get for the total amount of light coming from 

the system of systems a quantity proportional to — , and so for the 

kk' 

fcystem of system of systems we get a quantity proportional to 



^here k" is indefinitely large, n" very large. And for each successive 
order we get a multiplier of the form _, where k is indefinitely large 

K 

and n very large indeed. Suppose - to be the largest of all these multi- 



2 86 OTHER V/ORLDS THAN OURS. 

parts of our own sidereal system be beyond the ken of 
our most powerful instruments— and I have shown 

pliers, then the total amount of light received from the infinite system 
of systems is proportional to less than 



l( 



v y 2 v 



1+ « + i? 4 v — t0 infinit y)» 



(in which v is supposed to be less than tc), i. e., to less than - / _ — \ a 

k y k — v J 

finite quantity, which will even be minute if Jc and k are severally much 
greater than n and v. 

This particular mode of escaping from the difficulty suggested by 
the illumination of the heavens, without adopting the theory that light 
suffers extinction in its passage through space, occurred to me while I was 
preparing a series of papers entitled "A New Theory of the Universe," 
which appeared in The Student in the spring of 1869, and I there 
exhibit the considerations just dealt with. I was much pleased to find, 
from a letter of Sir John Herschel's, that the same idea had suggested 
itself to him ; as I was thus encouraged to believe that I had not gone 
very far astray in the whole series of papers, whereof the matter in ques- 
tion had seemed to me the most speculative portion. The following are 
the words in which Sir John Herschel, writing in ignorance of my having 
adopted the same view, expresses the ideas above dealt with : " One of 
the arguments advanced in favor of the spatial extinction of light was 
that, if there is not such extinction, the whole heavens ought to be one 
blaze of solar light — admitting the universe to be infinite, because it was 
contended that there could then be no direction in space in which the 
visual ray would not encounter a star (i. e., a sun). This argument is 
fallacious, for it is easy to imagine a constitution of a universe literally 
infinite which would allow of any amount of such directions of penetra- 
tion as not to encounter a star. Granting that it consists of systems 
subdivided according to the law that every higher order of bodies in it 
should be immensely more distant from the centre than those of the next 
inferior order — this would happen. Thus, in our own, the moon is very 
near the earth, the satellites to their primaries. These primaries are 
immensely more distant from the sun, their centre ; the fixed stars 
again still more immensely more remote from the sun. Suppose our 
system to terminate with the visible fixed stars ; then imagine a system 
of such systems as remote from each other, in comparison with their owv. 
dimensions, as the distance of the fixed stars in comparison with the 
planetary system ; such systems seen from each other would subtend 
eo greater angle than a star seeD from the sun — and so on." 



THE NEBULAE. 287 

that there are strong reasons for this conclusion — then 
the component suns of external galaxies cannot by any 
possibility be visible. So that, according to this view, 
all resolvable nebulae, at least, must be dismissed from 
the category of external galaxies. Nor will it be 
thought probable that irresolvable nebulae are external 
galaxies, if once that view of the extent of the sidereal 
system is adopted. 

But there are independent considerations, on which 
I prefer now to dwell, for believing that all the nebulae 
belong to the sidereal system. 

It will hardly be necessary, let me remark in pass- 
ing, for me to point out how this matter is associated 
with the subject of other worlds. It is true that, when 
once it is admitted that there are external galaxies, it 
may be looked on as a matter of small importance (so 
far as the subject of this treatise is concerned) whether 
we can actually see those galaxies or not. I am not, 
for instance, in the same position as Dr. Whewell, 
who assigned to the nebulae what I take to be their 
true place in the universe, with the express object of 
overthrowing the belief that there exist other galaxies 
as vast as the sidereal or vaster, thronged with suns 
which are severally the centres of planetary systems, 
within which again are worlds as well suited to be the 
abode of life as this earth on which we dwell. But. 
though my purpose is different from his, it is equally 
necessary that I should insist on the true position of 
the nebulae. Because, if these objects form indeed part 
of the sidereal system, the relations they present are 
of extreme importance. They exhibit to us within the 



288 OTHER WORLDS THAN OURS. 

bounds of our galaxy systems altogether different from 
the solar system, and thus suggest ideas of other 
classes of worlds peopled with their own peculiar forms 
of life, as distinct, perchance, even in their general char- 
acteristics, from any found amid the systems circling 
round stars, as the forms of life in Yenus or in Mars 
must be in their special characteristics from those ex- 
isting on our own earth. 

Freed from those analogies which led the elder 
Herschel to regard the stellar nebulae — resolvable and 
irresolvable * — as external star-systems, let us consider 
the relations presented by these and other nebulae, 
without reference to preconceived opinions. 

We must first pay attention to one of the most 
striking of the discoveries which the spectroscope has 
yet enabled man to make — the discovery that certain 
nebulae are gaseous. It is necessary to consider this 
significant discovery, rather than those which were the 
first to exhibit the real place of the nebulae in our 
scheme, because we shall thus be able to divide the 
nebulae at once into two great classes, instead of being 
led to this arrangement by following out the history 
of those long processes of research by which the two 
great orders of nebulae were long since separated from 
each other under the piercing scrutiny of Sir William 
Herschel. 

The reader will see how the spectroscope could at 

* By irresolvable stellar nebulae, I mean those nebulae which, though 
not resolvable into stars, yet present the characteristic features which 
lead astronomers to believe that only increase of telescopic power is 
needed in order to effect resolution. 



THE NEBTJLJE. 289 

once resolve a question which ordinary observations 
would be all but powerless to deal with. The nebulae 
being self-luminous, the nature of the matter which is 
the source of their light would be shown by the char- 
acter of the spectrum, as distinctly as though that 
matter were actually present in the laboratory of the 
spectroscopist. 

Mr. Huggins thus describes the observation which 
first revealed the true nature of certain orders of the 
nebulae. The object under examination was a nebula 
in Draco, belonging to the class of planetary nebulae : 
" On August 19, 1864, I directed the telescope, armed 
with the spectrum apparatus, to this nebula. At first 
I suspected some derangement of the instrument had 
taken place, for no spectrum was seen, but only a 
short line of light perpendicular to the direction of 
dispersion (that is, to what would in the case of solar 
light be the length of the spectrum). I then found 
that the light of this nebula, unlike any other ex-ter- 
restrial light which had yet been subjected by me to 
prismatic analysis, was not composed of light of differ- 
ent refrangibilities, and therefore could not form a 
spectrum. A great part of the light from this nebula 
is monochromatic, and after passing through the 
prisms remains concentrated in a bright line, occupy- 
ing the position of that part of the spectrum to which 
its light corresponds in refrangibility. A more care- 
ful examination, however, showed that — a little more 
refrangible than the bright line, and separated from it 
by a dafk interval — a narrower and much fainter line 
occurs. Beyond this again, at about three times the 
19 



2 9 o OTHER WORLDS THAN OURS. 

distance of the second line, a third exceedingly faint 
line was seen. The positions of these lines in the 
spectrum were determined by a simultaneous com- 
parison of them in the instrument, with the spectrum 
of the induction-spark taken between electrodes of 
magnesium. The strongest line coincides in position 
with the brightest of the air-lines. This line is due to 
nitrogen. . . . The faintest of the lines of the nebu- 
la agrees in position with a line of hydrogen. The 
other bright line was not found to correspond with a 
known line of any terrestrial element. Besides the 
bright lines, an exceedingly faint spectrum was just 
perceived for a short distance on both sides of the 
group of bright lines. Mr. Huggins suspected that 
this was not uniform, but crossed with dark spaces. 
Subsequent observations on other nebulae* induced 
him " to regard this faint spectrum as due to the solid 
or liquid matter of the nucleus, and as quite distinct 
from the bright lines into which nearly the whole of 
the light from the nebula is concentrated." 

* One of the most interesting of Mr. Huggins's researches into the 
subject of the light of nebulae is his attempt to determine its intrinsic 
brilliancy. By comparing the lijht of certain gaseous nebulge with that 
of a sperm-candle (of the size called six to the pound), he found that 
these objects, assumed to be continuous, shine with a light varying in 
intrinsic brilliancy from the 1,500th to the 20,000th of that of such a 
candle. By a strange misconception, Mr. Lockyer, in discussing Mr. 
Huggins's result, speaks of the comparison as though it related to the 
absolute brightness of the nebulas, saying that " such a candle a quarter 
of a mile oif is 20,000 times more brilliant than the nebula." Mr. Hug- 
gins's result is wholly distinct from this, and much more important. 
His comparison relates to the intrinsic luminosity of the nebular sub- 
stance, not to the quantity of light received from the nebulas. (The dis- 
tance of the candle in Mr. Huggins's observations is not considered in 
the result ; it was a mere matter of convenience.) 



THE NEBULjE. 291 

Thus was solved a problem which had, for the best 
part of a century, perplexed astronomers. There was 
not, indeed, a full answer to all the questions of in- 
terest associated with the problem. But it had been 
laid down by Sir William Herschel, as a legitimate 
conclusion from observation, that certain orders of the 
nebulae are gaseous, and astronomers had ranged 
themselves for and against this proposition. Telesco- 
pic improvements had seemed at length to tarn the 
scale in favor of those who held Sir William Herschel 
to have been mistaken. Already the problem had 
seemed all but definitively settled. And then in a mo- 
ment this observation by Mr. Huggins had reversed 
the whole matter. It was now established, beyond all 
possibility of future question, that, on the main point, 
the greatest of modern astronomers had been alto- 
gether in the right. 

The orders of nebulas which give a spectrum of 
bright lines, would seem from Mr. Husfsrins's observa- 

O ' Oct) 

tions to be (i.) the planetary nebulas, (ii.) the ring 
nebulae, (iii.) the irregular nebulae. The spiral nebulae 
seem, for the most part, to give a continuous spec- 
trum, but some of these objects give the bright-line 
spectrum indicative of gaseity. The orders of nebulae 
which give a continuous spectrum appear to be the 
following : (i.) star groups, (ii.) clusters, regular and 
irregular, and (iii.) easily resolvable nebulae. Of the 
irresolvable nebulae a large proportion seem to be gas- 



* The following classification of nebulae in this respect, by Lord Ox- 
mantown, is interesting as indicating the results of observations made 



ig2 OTHER WORLDS THAN OURS. 

Here, then, we find the nebulae ranged into two 
important divisions, apparently separated by a dis- 
tinct line of demarcation. Yet one is tempted to in- 
quire whether these divisions may not in reality run 
into each other, by the fact that among nebulee of cer- 
tain orders are objects belonging to both divisions. 
And the fact that, beneath the bright-line spectrum 
of the gaseous nebulas, a faint continuous spectrum 
may be seen, seems also to point in the same direc- 
tion. We know that, so far as the telescopic appear- 
ance of the nebulas is concerned, there is very striking 
evidence of a gradual progression from clusters to irre- 
solvable nebulas, and, therefore, we are led to inquire, 
whether the spectroscope conveys a similar lesson. 

Now, this question could only be answered satisfac- 
torily by the observation of a series of nebulae having 
spectra progressively varying, from bright lines on an 
almost invisible continuous spectrum to a continuous 
spectrum with the same bright lines superposed on it, 
but almost imperceptible, because their brightness so 
little exceeded that of the continuous spectrum. We 

with so powerful an instrument as the great Parsonstown telescope (the 

Bix-feet reflector) : 

Continuous Gaseous 
Spectrum. Spectrum, 

Clusters .... . . 10 

Certainly or probably resolved ? . .5 

Certainly or probably resolvable ? .10 6 

Blue, or green, no resolvability . 4 

No resolvability detected . 6 5 

Total observed .... 31 15 

Adding nebulae not observed at Parsonstown, there are in all 41 which 
exhibited a continuous spectrum, and 19 whicb gave a spectrum indica- 
tive of gaseity. 



THE NEBULM 293 

have not evidence of such completeness. But Lieu- 
tenant Herschel has observed in the southern heavens 
a clustering nebula with a continuous spectrum, on 
which he could just detect the three bright lines seen 
in the spectra of the gaseous nebulae. And, so far aa 
this evidence extends, the conclusion is obvious, that 
the various orders of nebulse are orders of but a single 
family. It will be seen presently that this conclusion, 
which is strikingly corroborated by other evidence, 
has a very important bearing on the views we are to 
form respecting the relations between the nebulse and 
the sidereal system. 

The first process by which we must attempt to 
form a correct estimate of the nebular system corre- 
sponds to Sir William Herschel's process of star-gaug- 
ing. We must inquire according to what general 
laws the nebulae are spread over the vault of heaven. 

Now, when this is done, it appears that there is a 
well-marked peculiarity in the arrangement of the 
nebulse, a peculiarity as striking as the existence of 
the galactic circle itself. The nebulae seem to withdraw 
themselves from the neighborhood of the galaxy. In 
the northern heavens they cluster very definitely 
toward the pole of the galaxy ; in the southern they 
are arranged in streams and clustering aggregations, 
but the galaxy itself is, in either case, left almost clear 
of nebulse. 

If this peculiarity is accidental, the coincidence 
involved is most remarkable. Had there been a zone 
of nebulse, and that zone had shown a tendency to 
coincidence with the Milky Way, the relation would 



294 OTHER WORLDS THAN OURS. 

have been held strikingly indicative of a real associa* 
tion between the nebnlar and the sidereal systems. 
But is the direct converse of this relation more likely 
to be the effect of chance ? Have not observers and 
experimenters concluded (in every other similar in- 
stance) that a law of contrast is as indicative of a real 
connection as a law of association ? It is surprising, 
therefore, that nearly all astronomers, who have con- 
sidered the relation in question, have regarded it as 
affording strong evidence that the nebular system is 
wholly dissociated from the sidereal. 

Next let us turn to special features. In the first 
place, let us inquire whether the different orders of 
nebulae exhibit any peculiarities of arrangement. 

We find that clusters exhibit a very marked pref- 
erence for the neighborhood of the Milky Way ; re- 
solvable nebulas seem to prefer the galactic zone, but 
not in so decided a manner ; and it is only among the 
irresolvable nebulse that we recognize that withdrawal 
from the Milky "Way which had seemed character- 
istic of the whole nebular system, before we consid- 
ered its several orders. The fact that the irresolvable 
nebulas form about four-fifths of the total number will 
account for the circumstance that a peculiarity really 
appertaining to that order alone should appear to be- 
long to the whole system of nebulas. 

Again, the planetary and irregular nebulas are 
found to affect the neighborhood of the Milky Way. I 
have already mentioned that these objects are gaseous. 

It is easy to see what general conclusions may be 
deduced from the peculiarities here touched upon. 



THE NEBULAE. 295 

Obviously the first shows us most distinctly that there 
is a relation between propinquity to the Milky Way 
and the character of nebulae as respects resolvability — 
a relation which points in the most decisive manner 
to the existence of a close association between the side- 
real system, of which the Milky "Way certainly forms 
part, and the nebular system, from which clusters and 
resolvable nebulae cannot reasonably be separated. It 
is equally obvious that the second peculiarity indicates 
the existence of a close association between the Milky 
Way and the character of the nebulae as respects ga- 
seity ; a relation which brings all the gaseous nebulae 
into close association with the sidereal system, since 
we know that among the extra-galactic nebulae there 
are many which are principally formed of the very 
same gases which appear in the irregular and planet- 
ary nebulae. When we consider that those peculiar- 
ities of configuration and of constitution which have 
alike seemed to indicate that the various orders of 
nebulae merge into each other by indefinable grada- 
tions are both associated, in a very distinct manner, 
with the most marked peculiarity of the sidereal sys- 
tem, and when to this we add what has been already 
suggested by the relation of contrast between the ir- 
resolvable nebulae and the Milky Way, the conclusion 
seems forcibly impressed upon us that the nebular and 
the sidereal systems are but different parts of one sin- 
gle scheme. 

But I pass on to other evidence, independent of 
what has hitherto been adduced, and pointing with 
equal force to the same conclusion. 



89 6 OTHER WORLDS THAN OURS. 

In the northern heavens it is not very easy to ex- 
hibit any general law of arrangement associating the 
nebulae and the fixed stars. For reasons which yet 
remain to be detected, there are in fact many marked 
points of difference between the whole character of the 
heavens on the northern and on the southern side of 
the galactic zone. But even in the northern heavens 
one peculiarity has been remarked, which is well 
worthy of careful consideration. Sir William Her- 
schel, while prosecuting his series of researches among 
stars and nebulae, was struck by the circumstance 
that, after sweeping over a part of the heavens which 
was unusually barren, he commonly met with nebulae ; 
insomuch that it was his practice at such times to 
call to his assistant (his sister, Miss Caroline Herschel) 
to " prepare for nebulae." This peculiarity was noticed 
also by Sir John Herschel. 

Now, what are we to understand by such a relation 
as this ? Can we suppose that, owing to some strange 
accident, external galaxies have been placed always 
opposite the barest regions of the sidereal system \ Or, 
setting aside such a notion as obviously incredible, are 
we to imagine that, when searching over those barren 
regions, the astronomer has a better chance of detecting 
nebulae than where stars are more richly strewn, be- 
cause the sky is less filled with glare % We are forced 
to dismiss this notion, that the barren regions of the 
heavens are thus in a manner the spy-holes of the 
sidereal system, by the fact (presently, and for another 
purpose, to be dwelt on more at length) that in the 
Magellanic Clouds, where stars of all magnitudes are 



THE NEBULA 2 gy 

richly strewn, nebulae, even down to the very faintest 
orders, are more abundant than in any other region of 
the heavens. "We have, then, no other conclusion to 
form, but that the association thus observed between 
starless regions and richness of nebular distribution 
indicates a very close relation indeed between stars and 
nebulae ; that, in fact, the nebulae in a sense represent 
the missing stars / that the region where those nebulae 
appear has been drained of star-material, so to speak, 
in order to form them. 

In the southern heavens yet clearer proof exists 
of an association between the stellar and nebular sys- 
tems. We do not recognize in the northern skies any 
well-marked star-streams. In the southern skies, how- 
ever, such streams have been recognized from the 
earliest ages. The constellations Hydra and Eridanus, 
the two streams from the Water-can of Aquarius, and 
the band between the two fishes,* indicate how clearly 
the ancients traced certain well-marked star- streams. 
The moderns have traced the extension of some of 
these streams in the constellations Grus, Hydra, Re- 
ticulum, etc., into the near neighborhood of the south- 
ern pole. Now, the nebulae in the southern heavens 
exhibit a well-marked tendency to aggregate into 
streams. So that, in this mere resemblance between 
the general characteristics of the stellar and nebular 
systems in the southern heavens, we have a somewhat 
remarkable evidence of association. But when we 

* Though Pisces is not a southern constellation, yet it is south of 
the galactic circle, to which I am for the moment referring the con 
stellations. 



j 9 8 OTHER WORLDS THAN OURS. 

consider the disposition of the two sets of streams — 
the stellar and the nebular — this evidence is very 
much strengthened. There is found to be a well- 
marked correspondence between the nebular and stel- 
lar streams, not merely as respects general position, 
but even in minute details — the nebular streams fol- 
lowing the windings of the stellar ones. Such a rela- 
tion would be very remarkable, even were it observed 
but in a single instance. Since, however, all the well- 
marked star-streams in the southern heavens are asso- 
ciated with well-marked nebular streams, no doubt 
can remain that the relation is not a mere coincidence, 
but indicates a real association between the nebular 
and stellar systems. 

But yet more striking evidence remains to be con- 
sidered. 

In the southern heavens there are two strange 
clouds of milky light, which have long been known 
by sailors as the Magellanic Clouds, but are commonly 
called by astronomers the Nubeculse. Each of these 
objects, when examined with the telescope, is found 
to be constituted, like the Milky Way, of multitudes 
of small stars. But, unlike the Milky Way, the 
Niibeculse contain within their bounds many nebulae 
of all orders. In fact, each of the Nubecula is at 
once a star-cluster and a cluster of nebulse. 

Now, there can be no doubt whatever that the as- 
sociation here is not accidental, that we do not by 
some strange chance see a great star-cluster in the 
same direction as a much more distant and much 
vaster cluster of external galaxies. JSTor, again, can 



THE NEBULJS. 299 

there be any doubt that the generally circular figure 
of each Nubecula indicates a general approach to the 
spherical form in the case of each cluster. The prob- 
ability that by some strange accident a cluster of 
cylindrical shape * might be so placed as to exhibit to 
us a circular figure is exceedingly small ; but the 
chance that two such clusters should be presented in 
so exceptional a manner may be regarded as evanes- 
cent. We are compelled, then, to believe that, within 
the limits of spheres so placed as to subtend a small 
angle to the eye, stars of all magnitudes between the 
seventh and the twelfth inclusive are mixed up with 
nebulas of all degrees of resolvabilitv. " Taking the 
apparent semi-diameter of the Nubecula Major at three 
degrees," says Sir John Herschel, " and regarding its 
solid form as, roughly speaking, spherical, its nearest 
and most remote parts differ in their distance from us 
by a little more than a tenth part of our distance from 
its centre." "It must therefore be taken as a demon- 
strated fact," he adds presently, " that stars of the 
seventh and eighth magnitude and irresolvable nebulas 
may coexist within limits of distance not differing in 
proportion more than as nine to ten." This demon- 
strated fact of Sir John Herschel's is the very fact to 
which I had been led by other considerations, the fact, 
namely, that the nebulas are not external galaxies, but 
intimately associated with the sidereal system of 
which in fact they form part and parcel. Dr. TVTie- 
well, accepting Sir John Herschel's reasoning as con- 

* Or, more correctly, a cluster shaped like a long frustum of a gigan- 
tic cone. 



joo OTHER WORLDS THAN OURS. 

elusive on the point, adopted the same view. Yet Sir 
John Herschel himself seems, immediately after estab- 
lishing' this noteworthy conclusion, to have been pre- 
pared to abandon it, at least as a demonstrated fact, 
since he says of it only that " it must inspire some de- 
gree of caution in admitting as certain " facts directly 
opposed to it. It must not be forgotten, however, 
that to the clear vision of this great astronomer the 
association between nebulae and fixed stars had pre- 
sented itself as a demonstrated fact ; that even in the 
latest editions of his noble work on astronomy, he has 
not altered the words in which he has spoken of that 
association ; and that so able a reasoner as Dr. Whe- 
well has chosen rather to accept what Herschel has 
spoken of as a demonstrated fact, than to adopt that 
measure of caution which Herschel subsequently ad- 
vocated. 

Lastly, and perhaps most strikingly of all, the asso- 
ciation between stars and nebulae is indicated by the 
obvious connection between the figure of the irregular 
nebulae and the arrangement of the star-groups seen 
in the same field of view. There is not one of the 
irregular nebulae which does not exhibit this pecu- 
liarity in the most striking manner. This may be 
asserted even of those nebulae with respect to which 
Sir John Herschel has remarked that the arrangement 
may be, and probably is, purely accidental. His own 
pictures prove in the most convincing manner that no 
such explanation can be accepted. Were the peculi- 
arity confined to the feature Herschel limits his atten- 
tion to, one might adopt his explanation. The mere 



THE NEBULA. ^o, 

aggregation of a large number of stars on the very 
heart of a nebula might be an accident. The fact, 
for instance, that the great irregular nebula surround- 
ing the star Eta Argus agrees exactly in position 
with the greatest condensation of the wonderfully rich 
portion of the Milky "Way on which that surprising 
variable lies, might be a mere coincidence, though in 
any case it would be a strange one. But when one 
examines the structure of this and similar nebulae, and 
finds that the stars are arranged in a manner most ob- 
viously related to the arrangement of the nebular con- 
densations (or folds as one may almost say), one can- 
not doubt that a real and intimate bond of association 
exists between the stars and the nebulous masses 
around them. If the extension of the milky light of 
the great Orion nebula to the star in the sword, which 
is centrally involved in strong nebulosity, to e in the 
belt, which is similarly involved, and to several other 
stars in the constellation all alike in being regions 
of increased nebular condensation, be a mere acci- 
dental coincidence, then the laws of probability had 
better be forgotten as soon as possible, for, as at pres- 
ent understood, they can only serve to lead men 
astray. 

In the accompanying plate is given a picture of 
the nebula, Messier 17, as observed with Lassell's 
four-feet reflector at Malta. I have selected it as af- 
fording a very striking instance of the particular form 
of association I have just been dealing with. !No one 
can, I think, refuse to recognize the fact that the sys- 
tem of stars shown in this drawing is not accidentally 



302 OTHER WORLDS THAh OURS. 

seen projected on a distant galaxy, but forms part and 
parcel of the nebula itself. 

It will be noticed, as respects the two proofs on 
which I have last dwelt, that they seem directly op- 
posed to those which I first qnoted. One cannot 
argue, it might be urged, that the nebulae are asso- 
ciated with the sidereal system because they are least 
numerous where there are most stars, and vice versa; 
while at the same time one draws the same conclusion 
from the aggregation of the nebulae in streams or clus- 
ters where there are streams and clusters of' stars, or 
from the fact that stars are seen actually mixed up 
with nebulous matter. At first sight this objection 
seems just ; but, on consideration, it will be found that, 
in reality, the two seemingly contrary lines of argu- 
ment bear in the same direction. When we find the 
nebulae gathered where stars are wanting, and vice 
versa, we conclude that there is some reason for this 
peculiarity, and that that reason must involve some 
sort of association between the nebulae and the stars ; 
we see, further, that the relation is accounted for if we 
suppose that, in these cases, either the formation of 
nebulae has drained a region of material from which 
single stars would otherwise have been formed, or vice 
versa. Why, in a particular region, the formation of 
nebulae should be encouraged, while the formation of 
stars should be checked, we cannot say; nor can we 
account for the contrary peculiarity in another region ; 
but we feel certain that some cause must exist for both 
relations, because the results are too marked to be the 
result of accident. Now, in the case where we find 



THE NEBULJE. 303 

both stars and nebulae abundant in particular parts of 
the heavens, we feel equally certain that the result is 
not accidental. Even though there were not here, as 
in the former case, the evidence of a clearing of star- 
material from certain regions, we could not doubt that 
the association of stars and nebulae was real and not 
apparent. But in reality there is here, precisely as in 
the former case, a gathering together of stellar matter 
into certain regions. The very existence of such a 
stream as Eridanus or Hydra, and of such a cluster as 
the greater or lesser Magellanic Cloud, implies the ac- 
tion of such a process of segregation. A stream would 
not be recognizable if it were not bounded by relatively 
bare regions. Clusters like the Xubeculae might be 
visible even on a rich sky, and were the sidereal heav- 
ens richly strewed with stars round these objects I 
should be disposed to admit that there was a difficulty 
in my theory. But what is the fact? Xot only is 
each of the ISTubeculae placed in a region obviously 
bare of lucid stars, but Sir John Herschel, speaking of 
the telescopic aspect of the neighborhood of these mys- 
terious clusters, dwells again and again on its poverty. 
" A miserably poor and barren region," he says of one 
field near the IN'ubeculae. " The access to the E"ubec- 
ulae," he says elsewhere, "is on all sides through a 
desert" What evidence could more clearly point to 
the fact that these great clusters are gathered out 
from a vast region of space? Their internal structure 
teaches us how such a process of segregation leads to 
the birth of nebulae, as well as stars. The whole his- 
tory of the sidereal system is indeed taught us in the 



3°4 



OTHER WORLDS THAN OURS. 



Magellanic Clouds and the great streams of inter- 
mixed stars and nebulae which flow toward them as 
rivers toward some mighty lake. We see the wonder- 
working forces of gravitation extending their influ- 
ences throughout vast regions of space, gathering in 
the materials spread throughout that space, here form- 
ing stars, there nebulae, changing the element of dis- 
tance into various forms of force — heat and light, 
electricity and magnetism — and finally (though in 
what special way we are as yet unable to perceive) 
making the orbs which it has formed the seats of life, 
or subservient, more or less directly, to the wants of 
living creatures. 



CHAPTER XIII. 



SUPERVISION AND CONTEOL. 



It has been customary, in treatises on the plural- 
ity of worlds, to discuss the religious difficulties which 
seem to suggest themselves wheu man regards the uni- 
verse around him as thronged with worlds, each peo- 
pled with millions of living creatures, and many per- 
chance the abode of intelligent and therefore respon- 
sible beings. Accustomed to regard himself as in a 
special manner the object of God's care and solicitude, 
it is not without a sense of pain that he is brought to 
contemplate the possibility that other creatures may 
exist in uncounted millions whom God regards with 
infinite love and interest. " If this be so," asks Whe- 
well, "how shall the earth and men, its inhabitants, 
annihilated as it were by the magnitude of the known 
universe, continue to be any thing in the regard of 
Him who embraces all ? Least of all, how shall men 
continue to receive that special, preserving, providen- 
tial, judicial, personal care, which religion implies ; 
and without the belief in which, any man who has re- 
ligious thoughts must be. disturbed and unhappy, deso- 
late and forsaken % " 
20 



306 OTHER WORLDS THAN OURS. 

I do not, however, feel by any means invited to 
consider " the religious difficulty " by the success which 
has attended the efforts made by others to remove it. 
I find that, while, on the one hand, the thoughtful 
and conscientious men who have in a special manner 
considered the difficulty have been (in relation at 
least to revealed religion) at issue among each other, 
their views have not, on the other hand, been found 
acceptable even by a few among their readers. I 
doubt almost, when I judge from the comments which 
have been made on this part of the works of Chal- 
mers, Whewell, Brewster, and others, whether a sin- 
gle reader of those works has found the religious 
views of any one of their authors congenial with his 
own. 

It is specially noteworthy that even where, as 
in the case of Brewster and Chalmers, two writers 
adopt the same view of the general question of other 
worlds, they yet hold altogether different views as to 
the bearing of that question upon the subject of 
religion. 

It is very doubtful, therefore, whether it is a wise 
thing, whether it is conducive to the purpose of any 
one thus conscientiously discussing the religious aspect 
of our question, to present his own personal views 
on the subject of revealed religion. If I thought 
otherwise, I should not shrink from the task of indi- 
cating the sufficiently definite views which I entertain 
myself upon this subject. But I apprehend that, apart 
from the consideration that the reader must be wholly 
indifferent about them, my indicating them would have 



SUPERVISION AND CONTROL. 307 

an effect the very reverse of that which I should 
desire.* 

Merely remarking, therefore, that in considering 
the infinity of God's beneficence we must remember 
this quality of infinity, that it comprises many infini 
ties, I pass on to considerations which seem to fall 
more naturally within the province of the student of 
science. 

It is a peculiarity of the subject of other worlds 
than ours, that it suggests, more strikingly than any 
other, certain difficulties in connection with the con- 
ceptions we are to form as to the supervision and con- 
trol exercised by the Creator over His works. We 
feel that if we are to believe, as we must believe, in 
an infinitely powerful and wise God, we must not 
merely regard all the worlds which people space as 
objects of His regard, but every event, however seem- 
ingly insignificant, occurring in any, even the least 
important of His worlds, as an essential part of the 
plan according to which all things were created from 
the beginning. 

* Where Bacon has selected to be silent, few can without presump- 
tion venture to lay down their opinions as of weight in matters con- 
nected with revealed religion. The argument which follows may not 
indeed be acceptable to many, but few will doubt the wisdom of the con- 
clusion to which he comes. " If we were disposed," he says, "to sur- 
vey the realm of sacred or inspired theology, we must quit the small 
vessel of human reason, and put ourselves on board the ship of the 
Church, which alone possesses the Divine needle for justly shaping the 
course. Nor will the stars of philosophy, that have hitherto principally 
lent their light, be of further service to us ; and therefore it were 
not improper to be silent upon the subject." — Advancement of Learning, 
Book IX. 



3 o8 OTHER WORLDS THAN OURS. 

But here already — such is the nature of the subject 
I am to deal with — I have been forced to use terms 
which have really no proper application to the Al- 
mighty and His works. I have spoken of the creation 
of all things, whereas, in the sense in which men can 
alone interpret such words, we cannot reasonably con- 
ceive that there ever was a creation ; and I have 
spoken of the beginning, whereas we cannot conceive 
that there ever was a beginning in the sense implied.* 

Let us consider definitely (even though we must be 
unable to conceive clearly or at all) the infinities we 
have to deal with. 

"We know that space must be infinite. If the re- 
gion amid which stars and nebulae are scattered with 
so great profusion be limited, if beyond lies on all sides 
a vast void, or if, instead, there be material bounds 
enclosing the universe of worlds on every hand, yet 
where are the limits of void or bound ? Infinity of 
space, occupied or unoccupied, there must undoubted- 
ly be. Of this infinity it has been finely said, that its 
centre is everywhere, its boundary nowhere. Now, 
whether within this infinity of space there be an infin- 
ity of matter, is a question which we cannot so cer- 
tainly answer. Only, if we were to accept this as cer- 
tain, that the proportion which unoccupied bears to 
occupied space cannot be infinitely great — a view 
which at least seems reasonable and probable — then it 
would follow that matter as well as space must be in- 

* To prevent any possibility of my meaning being misinterpreted 
here, I point out that I have been obliged myself to use the terms of 
which I speak as inexact. 



SUPERVISION AND CONTROL. 309 

finite, since any finite proportion of infinity must it- 
self also be infinite. So that, regarding occupied space 
as the realm over which the Almighty's control is ex- 
ercised, and over which His supervision extends, we 
find just reason for looking upon that realm as no less 
infinite than the infinity of space in which it is con- 
tained. 

Time also must undoubtedly be infinite. If the 
portion of time which has hitherto been, or which will 
hereafter be, occupied with the occurrence of events 
(of whatever sort) were preceded and will be followed 
by a vast void interval, yet there can be neither be- 
ginning nor end to either of those bounding voids. 
Infinity of time, occupied or unoccupied, there must 
undoubtedly be. And, though it is not possible for us 
to know certainly that there has been no beginning, 
or that there will be no end to that portion of time 
which is occupied with the occurrence of events (of 
whatever sort), yet it appears so unreasonable to con- 
ceive that unoccupied time bears an infinitely great 
proportion to occupied time, that we seem forced to 
the conclusion that occupied time is infinite — or, more 
definitely, that there has been no beginning and will 
be no end to the sequence of events throughout the 
infinitely-extended realm of the Almighty. 

And thus we are forced to believe in the infinite 
wisdom and the infinite power of God ; since to con 
ceive of limits to the wisdom and power of Him whose 
realm is infinite in extent and in duration, is obviously 
to conclude that the Ruler is infinitely incompetent to 
rule over His kingdom ; for there can be no relation 



3 1 ' 



OTHER WORLDS THAN OURS. 



between the finite and the infinite save the relation of 
infinite disproportion. 

Now, although the conception of God as a spirit- 
omnipresent, eternal, omnipotent, and omniscient — is 
altogether beyond the powers of man's imagination, 
yet we may consider certain relations between the way 
in which He views the universe and the modes in which 
we men consider the various matters falling either un- 
der our supervision and partial control, or of which 
we can in any way or to any extent become cognizant. 

Senses such as we have we can no more attribute 
to God than we can assign to Him hands and feet. 
Nor can we conceive in what way a spirit, as He is, is 
cognizant of material processes which we only recog- 
nize through their material effects. Yet, as we do not 
doubt that God is cognizant of the actual state of the 
universe at any moment, we cannot doubt that He is 
cognizant of all those processes by which our senses 
can be affected. And clearly, He not only recognizes 
all these processes in such sort that he may be said to 
see what we see, to hear what we hear, and so on ; but 
effects which, though related to vision, hearing, or the 
like, are infinitely too minute to be appreciated by our 
senses, must be as obvious to God as the light of day 
or the roar of thunder to ourselves. 

But, before considering the nature of God's super 
vision of His universe, we may proceed a step farther. 
The senses we possess are sufficient to indicate to us 
the possible existence of senses not merely far more 
acute, but of a wholly different kind. By the sense 
of touch, for instance, we can indeed recognize the 



SUPERVISION AND CONTROL. 31I 

feeling of heat ; but it is easy to conceive of a sense 
(analogous to that by which light is made to teach us 
of the aspect of external objects) enabling men to judge 
of the figure, substance, internal structure, and other 
qualities of an object, by the action of the heat-waves 
proceeding from it. Or again electricity might, in- 
stead either of light or of heat, be the means of com- 
municating intelligence as to the qualities of objects. 
"We can conceive also of a sense bearing the same 
analogy to sight that the spectroscope bears to the 
telescope. And a hundred kinds of sense, or in other 
words, a hundred modes of receiving intelligence about 
what exists or is going on around us, might be readily 
conceived. Now, we cannot doubt that the natural 
processes involved in every such mode of conveying 
impressions to material creatures must be infinitely 
more obvious to God than we can possibly conceive 
them to be to material beings. 

Yet once more, we know that reason is able to range 
beyond the action of the senses. Man is able to assure 
himself that events have happened which yet have 
produced no direct effect upon any of his senses. By 
the exercise of reason he becomes as well assured of 
such events as though they had actually passed before 
his eyes. We must assume that an analogous power, 
but infinite in degree, infinitely rapid in its operation, 
and infinite in the extent of space and time over which 
it ranges, is possessed by the Almighty. 

And now let us notice some of the conclusions to 
which these considerations tend. 

Let us first deal with the teachings of that sense 



312 



OTHER WORLDS THAN OURS. 



which is the most far-reaching * of all the faculties 
given to man — the sense of sight. 

In a little treatise called " The Stars and the Earth," 
published anonymously several years since, some re- 
sults of modern discoveries respecting light were dealt 
with in a very interesting manner. I propose to fol- 
low the path of thought indicated in that treatise, as a 
fitting introduction to wider conceptions of the super- 
vision and control exercised by the Almighty over his 
universe. 

We know from Eomer's researches, and even more 
surely from the phenomenon termed the aberration of 
the fixed stars, that light does not travel with infinite 
velocity. Its speed is indeed so enormous, that, com- 
pared with every form of motion with which we are 
familiar, the velocity of light appears infinitely great. 
In a single second light traverses a space equal to 
eight times the circumference of the earth ; and there- 
fore, in travelling from any visible object on the earth 
to the eye of a terrestrial observer, light occupies a 
space of time indefinitely short. Yet, even as regards 
such objects as these, light has occupied a real interval 
of time, however minute, in reaching the eye ; inso- 
much that we see objects not as they are at the mo- 
ment we perceive them, but as they were the minutest 
fraction of a second before. 

* Most persons, if asked which sense comes next to sight in this re- 
spect, would answer hearing. Yet touch — or rather feeling— has a range 
far exceeding that of hearing, since we can feel the heat emitted by the 
sun. Nor is it difficult to conceive of such an increase in the delicacy of 
the sense of touch, that even the minute amount of heat received from 
the tixed stars might be felt, and so the range of the sense extended 
many million-fold. 



SUPERVISION AND CONTROL. 3^ 

Raising our eyes from the earth to regard the celes- 
tial objects, we find, in place of the indefinitely minute 
interval before considered, a really appreciable space 
of time occupied by light in carrying to us information 
as to the condition of those distant orbs. From the 
moon, light takes little more than a second and a 
quarter in reaching us, so that we obtain sufficiently 
early information of the condition of our satellite. 
But light occupies more than eight minutes in reach- 
ing us from the sun, a longer or shorter interval in 
travelling to us from Mercury, Yenus, and Mars, ac- 
cording to the position of these planets, from about 
thirty-five to about fifty minutes in reaching us from 
Jupiter, about an hour and twenty minutes on the 
average in speeding across the great gap which sepa- 
rates us from Saturn, while we receive intelligence 
from Uranus and Neptune only after intervals respec- 
tively twice and three times as great as that which 
light takes in reaching us from the ringed planet. 

Thus, if we could at any instant view the whole 
range of the solar system as distinctly as we see Jupi- 
ter or Mars when in opposition, the scene presented to 
us would not indicate the real aspect of the solar sys- 
tem at that, or indeed at any definite instant. Pre- 
cisely as a daily newspaper gives us a later account 
of what is going on in London than of events happen- 
ing in the provinces, of these than of events on the 
Continent, and of these again than of occurrences tak- 
ing place in America, Asia, Africa, or Australasia, so 
the intelligence brought by light respecting the various 
members of the solar system belongs to different epochs 



p 4 OTHER WORLDS THAN OURS. 

And if man had powers of vision enabling him to watch 
what is taking place on the different planets of the solar 
system, it is clear that events of the utmost importance 
might have transpired— under his very eyes, so to 
speak— while yet he remained wholly unconscious of 
their recurrence. Or, to invert the illustration, if an 
observer on Neptune could see all that is taking place 
on the earth, he might remain for hours quite uncon- 
scious of an event important enough to affect the wel- 
fare of a whole continent, though that event should 
happen under his eyes, and his visual powers be such 
as I have supposed. We can imagine, for example, 
an observer on Neptune watching the battle of Water- 
loo from the early dawn until the hour when Napo- 
leon's heart was yet full of hope, and our great captain 
was watching with ever-growing anxiety, as charge 
after charge threatened to destroy the squares on whose 
steadfastness depended the fate of a continent. We 
can conceive how full of interest that scene would have 
been to an intelligent Neptunian, and how eagerly he 
would have watched the manoeuvres of either army 
and also, what neither army knew of, the approach of 
Blucher with his Prussians. Yet, while our Nep- 
tunian would thus have traced the progress of the bat- 
tle from his distant world, the conflict would in reality 
have been long since decided, the final charge of the 
British army accomplished, the Imperial Guard de- 
stroyed, Napoleon fugitive, and the Prussians, who to 
the Neptunian would be seen still struggling through 
muddy roads toward the field of battle, would be re- 
lentlessly pursuing the scattered army of France. 



SUPERVISION AND CONTROL. 



315 



It is, however, when we pass beyond the limits of 
the solar system that the non-contemporaneous nature 
of the scene presented to us becomes most striking 
Here we have to deal not with seconds, minutes, or 
hours, but with years, decades, and centuries. From 
the nearest of the fixed stars light takes fully three 
years in travelling to the earth. Even the star 61 
Cygni is so far from us that its light only reaches us in 
ten years. And, so far as observation has hitherto 
gone, it seems unlikely that, amid the whole host of 
heaven, there are so many as a hundred stars — lucid 
or telescopic — whose light reaches us in a shorter in- 
terval of time than twelve or fifteen years. Whatever 
views we form as to the arrangement of the sidereal 
scheme, whether those usually accepted be held to be 
correct, or whether I have been right in adopting 
others, there can be no doubt that, among the stars 
revealed to us by the telescope, there must be myriads 
which lie many times farther from us than the bright 
star in Centaurus and the orb in Cygnus which have 
been found relatively so near to us. In fact, the views 
I have adopted, respecting the wide range of magni- 
tude among the fixed stars, do not interfere in the 
least with the theories which have been formed as to 
the distances from beyond which the light of some of 
the stars, only just visible in powerful telescopes, must 
be supposed to reach us. On the contrary, one may 
conceive, according to my views, that some of these 
faintly-seen orbs may be many times larger even than 
giant Sirius, in which case the distance of such stars 
would be many times greater than has been hitherto 



jl6 OTHER WORLDS THAN OURS. 

supposed. We may at any rate assume with confi- 
dence that many stars only visible in powerful tele- 
scopes shine from beyond depths which light would 
occupy thousands of years in traversing. I cannot, 
indeed, go further, as astronomers have hitherto done, 
and say that the nebulae must be regarded as external 
galaxies, and therefore as sending their light to us 
over spaces which light must take many times as long 
an interval in traversing as it does in travelling to us 
from the bounds of our own galaxy. But it would be 
to misinterpret altogether the views which I have 
formed respecting the universe to suppose that I ima- 
gine those distant spaces which astronomers have 
hitherto filled with imaginary galaxies to be unten- 
anted. On the contrary, I have no doubt whatever 
that galaxies, resembling our own, exist at distances 
infinitely exceeding those at which astronomers have 
placed their most distant nebular universes, if even 
the bounds of our own galaxy do not extend into space 
as far as the widest limits hitherto assigned to the sys- 
tem of nebulae. So that I am not precluded from 
speaking of orbs whose light, though unrecognized by 
us, yet is ever pouring in upon the earth, conveying, 
though in letters we cannot decipher, or even trace, a 
message which has taken millions on millions of years 
in traversing the awful gulf beyond which lie those 
mysterious realms. 

If we conceive, then, that man's visual powers 
could suddenly be so increased that, without instru- 
mental aid, he could look around him into the celes- 
tial depths, piercing even to those outer galaxies which 



SUPERVISION AND CONTROL. 357 

astronomers have seen only imaged in the nebulje, 
how wide would be the range of time presented to him 
by the wonderful scene he would behold. There 
would blaze out Alpha Centauri with its record three 
years old ; there the star in Cygnus as it existed ten 
years since ; the whole host of stars known to man 
would exhibit records ranging from a few years to 
many centuries in age ; and, lastly, the external gal- 
axies, which are perhaps forever hidden from the 
searching gaze of man, would reveal themselves as 
they were ages on ages before man appeared upon the 
earth, ages even before this earth was framed into a 
globe, nay ages perhaps before the planetary system 
had begun to gather into worlds around its central 
orb. 

It is when we are thus contemplating in imagina- 
tion the whole expanse of the universe, and, as one 
may almost say, the whole range of past time, that 
the author of the little treatise I have spoken of in- 
vites us to consider two processes of thought having 
sole reference to this earth on which we live, and to 
that history which, though all-important to ourselves, 
seems to fade into such utter insignificance in the 
presence of the grand history of the orbs which lie in 
uncounted millions around us. 

To a being placed on some far-distant orb, whence 
light would occupy thousands of years to wing its 
flight to us, there would be presented, if he turned his 
gaze upon our earth, and if his vision were adequate 
to tell him of her aspect, the picture of events which 
thousands of years since really occurred upon her sur- 



3 i8 OTHER WORLDS TEAK OURS. 

face. For the light which left the earth at that time, 
winging its way through space with the account, if we 
may so speak, of those occurrences, is now travelling 
as swiftly as when it left our earth, but amid regions 
of space removed from us by a light-journey thou- 
sands of years in duration. And thus, to the observer 
on this distant orb, the events which happened in 
those far-off years would seem to be actually in prog- 
ress. 

But now conceive that powers of locomotion com- 
mensurate with his wonderful powers of vision were 
given to this being, and that in an instant of time he 
could sweep through the enormous interval separating 
him from our earth, until he were no farther from us 
than the moon. At the beginning of that tremendous 
journey he would be watching events which were 
occurring thousands of years since ; at its close he 
would gaze upon the earth as it was one second only 
before he undertook his instantaneous flight ; so that, 
in the course of his journey, he would gaze upon a 
succession of events which had occurred during those 
thousands of years upon the face of this little earth. 

The other conception is no less beautiful and strik- 
ing — I may remark, also, that it is, in a scientific 
sense, somewhat more exact. Suppose that a being 
armed with such powers of vision as we have imagined 
should watch fiom the neighborhood of our earth the 
progress of some interesting event. If he then began 
to travel from the earth at a rate equal to that at 
which light travels, he would see one phase of the 
event continually present before him, because he would 



SVPERVI8I0N AND CONTROL. ^9 

always be where the light-message recording that event 
was actually travelling. By passing somewhat less 
swiftly away, he would see the event taking place 
with singular slowness ; while by passing away more 
swiftly he would see the event occurring in inverted 
order. Suppose, for example, he were watching the 
battle ol Waterloo, he could gaze on the fine picture 
presented by the Imperial Guard as they advanced 
upon the English army, for hours, years, nay, for cen- 
turies or cycles ; or he might watch the whole prog- 
ress of the charge occurring so slowly that years might 
elapse between each step of the advancing column, 
and the bullets which mowed down their ranks might 
either seem unmoving, or else appear to wend their 
way with scarcely perceptible motion through the air ; 
or, finally, he might so wing his flight through space 
that the Guard would seem to retreat, their dead men 
coming to life as the bullets passed from their wounds, 
until at length the Old Guard would be seen as it was 
when it began its advance, in the assured hope of de- 
ciding Waterloo, as it had decided so many hard- 
fought battles for its imperial chief. 

It may seem hypercritical to notice scientific in- 
exactness in ideas professedly fanciful. But as the 
author lays some little stress upon the scientific truth 
of the method in which his fancies are exhibited, and 
as, further, he dwells upon two of the more obvious 
objections to the first conception, it may be well to 
consider a further objection, which enforces on us a 
total change in the way of presenting the idea. He 
remarks that the being he has conceived to be borne 



3 20 OTHER WORLDS THAN OURS. 

toward the earth through a distance so enormous, 
would not see in a moment the whole history of the 
earth during the thousands of years considered, but 
only the history of that hemisphere which was turned 
toward him ; while, further, all that took place under 
roofs or under cover of any sort, would remain unper- 
ceived by him. But there is a more serious objection. 
Among the events which have taken place during 
those thousands of years, have been thousands of revo- 
lutions of this earth around the sun, and more than 
three hundred and sixty-five times as many rotations 
of this earth upon her axis, to say nothing of the state- 
ly sway of the earth in her motion of precession. So 
that our imaginary observer would in reality see the 
earth whirling with inconceivable rapidity upon its 
axis, and sweeping with even more tremendous velo- 
city around the sun, so as to complete thousands of 
circuits in a single second. He would see clouds 
forming and vanishing in an amazing succession of 
changes, all occurring in a single instant. And, even 
though his powers of vision enabled him to pierce the 
cloud-envelope, he would not have a consecutive pre- 
sentment of the various events occurring in any part 
of the earth, but only a hap-hazard succession of half 
days for each portion of her surface. 

However, we can easily see that, by a slight modi- 
fication, the beautiful conception of our author can be 
made to illustrate one mode at least in which the 
events occurring upon our earth may be conceived to 
be at all times present to the thoughts of the Al- 
mighty. Imagine a sphere with a radius over which 



SUPERVISION AND COMROL. ~ 2 \ 

iglit would travel in the time which has elapsed since 
jving creatures first began to move upon this earth 
and having for centre the place occupied by the earth 
at that instant. Then, if we imagine millions of eyes 
over the surface of that sphere, all turned with pier- 
cing powers of vision upon the central earth, we see 
that to these eyes the earth would be presented by the 
record of light, not as she is now, but as she was at 
that primeval day. Now, conceive these millions of 
eyes closing swiftly in upon the earth, but with this 
peculiarity of movement that, instead of being always 
on a sphere around a fixed point, they were always on 
a sphere around the position which was really occu- 
pied by the earth, when the light-messages started 
which those eyes are receiving at the moment. Then 
if that wondrous sphere contracted in an instant, ac- 
cording to the law assigned it, until its myriad mill- 
ions of eyes were gazing intently on our earth from a 
sphere of but a few thousand miles in radius, the 
whole history of the earth, so far as light could render 
it, would have been in a moment of time presented 
before the myriad-eyed sphere. 

To apply this illustration to the subject we are 
upon. We know that the Almighty is present where 
the boundary of our great sphere was placed at first. 
Before Him the light-messages are presenting the 
account of the primeval earth. He also is present 
everywhere within the region through which the con- 
tracting sphere was conceived to pass. He therefore 
3ees the whole history of the earth as presented by the 
light-waves. We begin, however, already to feel that 
21 



322 OTHER WORLDS THAN OURS. 

we cannot say of Him what we said of the imaginary 
being first thought of, or of the myriad-eyed contract- 
ing sphere, that in a moment of time He can see the 
whole history of the earth successively presented before 
Him. As He exists throughout that space, there is 
no succession of time in His vision of the events tran- 
spiring on our globe. Past and present are one before 
Him ; and we shall soon see that present and future 
also must be one in His sight. 

But now, still considering only the information 
which light conveys as it travels onward through 
space, we see that what is true of our earth is true 
also of every orb throughout the universe. The whole 
light-history of every such orb must be present at 
every instant of time to the Creator who is omni- 
present. So that to the obvious conception that God, 
being everywhere, must be cognizant of all things, we 
have to add this further consequence of His omnipres- 
ence, that He must be cognizant of the history of 
all things, in the same sense that a man is cognizant 
of events which are passing before his eyes. 

And, by extending these considerations to other 
modes in which the history of an event is recorded, so 
to speak, by natural processes, we can see that a much 
more complete and definite picture of past events than 
light can convey, must be at all times present before 
the Almighty. A sense which could analyze heat-im- 
pressions as eyesight analyzes light, would tell us not 
only what eyesight tells us, but much that no light- 
messages can convey to us. At least it is conceivable 
that a sense of this sort would enable the being pro 



SUPERVISION AND CONTROL. 323 

rided with it to recognize not merely the nature of the 
surface of any body whose heat reached the organ of 
this sense, but the quality of the body's internal struct- 
ure, processes going on within the body, or the nature 
of bodies so placed that eyesight would not render us 
sensible even of their existence. Electricity, in like 
manner, would avail to give information altogether 
distinct from that which light can impart. And pre- 
cisely as, in considering light, we saw that the Creator 
must be supposed sensible of every light-record trav- 
elling through space, so, as regards these imaginary 
but conceivable senses, we must believe that any in- 
formation which they could by any possibility impart, 
must be conveyed to the omnipresent God. And 
further, it would be a contradiction to our belief in His 
infinite wisdom to suppose that the infinite multi- 
plicity of the records thus continually present before 
Him could in any way render their significance less 
distinct.* 

But, turning from the consideration that the Al- 
mighty, by virtue of His omnipresence, is thus cog- 
nizant, not merely of all that is at any moment taking 

* Moralizing may seem altogether out of place in such a work as this, 
but certainly one is tempted to dwell somewhat thoughtfully on the 
ideas raised by the considerations I have dwelt on above. It is not with- 
out a feeling of awe that one considers that the records of every action 
of our lives are not merely at this moment before God, but will for ever 
and ever be freshly present to Him : and that, not merely in the sense 
that He knows every thing (an idea too vague for man rightly to grasp), 
but by the action of physical processes such as our Faradays and 
Tyndalls deal with. May it not be through an instinctive recognition 
of this great truth, that man alone, of all the creatures which people 
this earth, feels contrition for long-past misdeeds, even where be has no 
fear of their ever bearing fruit in future sorrows ? 



3 24 OTHER WORLDS THAN OURS. 

place throughout the universe, but of all that haa 
taken place in the infinity of past time, we have to 
consider another mode in which the universe must be 
regarded as present before Almighty God. 

The senses by which we judge of what is going on 
around us are, after all, merely one means by which we 
judge of causes by their effects. When we say, for 
instance, that we have seen such and such an object, 
or watched such and such an event, what we really 
imply is, that we have recognized certain physical im- 
pressions, which we can only explain by the existence 
of that object, or by the occurrence of that event. 
We know, in fact, that in certain exceptional cases im- 
pressions resembling those caused by the actual pres- 
ence of an object, or by the actual occurrence of some 
event, may arise where no such object has been present, 
or where no such event has transpired. Still, we 
commonly feel safe from error, in concluding, from 
certain impressions conveyed to the mind by the agen- 
cy of the visual organs, that certain objects have been 
really present, at rest or in action, before us. 

But, then, even man, limited as are his powers, can 
yet follow a series of effects and causes far more nu- 
merous than those concerned in the act of vision ; and 
so he can become certain of the occurrence of past 
events of which no sense he possesses gives him any 
direct information. For example, though I neither 
saw the battle of Waterloo nor heard the thunder of 
the guns there, yet I am as certain that the battle 
really took place as though sight and hearing had 
given me direct information on the matter. And, 



SUPERVISION AND CONTROL. 325 

when I inquire whence that certainty arises, I find a 
complicated series of events involved in my acqui- 
sition of the knowledge that the battle took place 
My interpretation of the letter-press account of the 
battle involved in itself a number of more or less com- 
plex relations, associated with the question of my con- 
fidence in those who taught me that certain symbols 
represented certain letters, that certain combinations of 
letters represented certain words, and that certain words 
represented certain ideas. Not to follow out the long 
train of ideas thus suggested, it will be clear that, with 
regard to a variety of matters, the knowledge which 
any man has is associated with considerations of cause 
and effect, of general experience, of confidence in the 
accounts of others or in his own judgment, which are 
in reality of a highly-complex character. 

Now, we are led by these thoughts to remember 
that, independently of those records of past events 
which are brought continually before the Almighty 
by processes resembling those which directly affect 
our senses, such events must be recognizable by Him 
(even to their minutest details) in the consequences 
which they have led to. If a great naturalist like 
Huxley or Owen can tell, by examining the tooth of a 
creature belonging to some long-extinct race, not only 
what the characteristics of that race were, but the gen- 
eral nature of the scenery amid which such creatures 
lived, we see at once that a single grain of sand or 
drop of water must convey to the Omniscient the his- 
tory of the whole world of which it forms part. Nay, 
why should we pause here ? The history of that world 



3 26 OTHER WORLDS THAN OURS. 

is in truth bound up so intimately with the history of 
the universe, that the grain of sand or drop of watei 
conveys not only the history of a world, but with equal 
completeness the history of the whole universe. 

The Almighty, then, by virtue of His possessing in 
an infinite degree that quality which enables man to 
reason upon past events of which his senses bring him 
no direct intelligence, has the whole past history of the 
universe continually present before Him, in the state 
and position of each single atom throughout infinity 
of space.* 

Turning from the past to the future, we must not 
let the limited nature of our recognition of the course 
of future events prevent us from forming a just opin- 
ion as to the way in which the future must be always 
present before God. We can judge of the past by its 
effects, but we are almost utterly unable to judge of the 
future by its causes. Yet we cannot doubt that the 
future is present in its germs, precisely as the past is 
present in its fruits. It may be regarded in fact as 
merely a peculiarity of man's constitution that the 
past is more clearly present to his mental vision than 
the future. It is easy not only to conceive that the 
future and the past should be equally present to intel- 
ligent creatures, but to conceive of a form of intelli- 
gence according to which past events would be obliter- 
ated from the mind as fast as they took place, while 

* In fact, if we consider the matter attentively, we see that there 
cannot be a single atom throughout space which could have attained its 
present exact position and state, had the history of any part of the uni- 
verse, however insignificant, been otherwise than it has actually been, in 
even the minutest degree. 



SUPERVISION AND CONTROL. 



327 



the future should be as actually present as to the ordi- 
nary human mind the past is. 

In considering the Omniscient, however, all ques- 
tions of degree must be set on one side. The future 
must be as absolutely and essentially present to Him 
in its germs as the past has been shown to be in its 
fruits. If a grain of sand contains in its state, figure, 
and position, the picture of the universe as it is, and 
the whole history of the universe throughout the infi- 
nite past — and who can doubt that this is so 1 — it con- 
tains with equal completeness the history of the uni- 
verse throughout the infinite future. No other view 
is compatible with the assumption of the Almighty's 
infinite wisdom, and no assumption which limits the 
wisdom of God is compatible with our belief that He 
is supreme in the universe. 

Obviously also every event, however trifling, must- 
be held to contain in itself the whole history of the 
universe throughout the infinite past, and throughout 
the infinite future. For every event, let its direct 
importance be what it may, is indissolubly bound up 
with events preceding, accompanying, and following it, 
in endless series of causation, interaction, and effect. 

So far, then, as the Almighty's watch over His 
universe is concerned, we have two lines of thought, 
each leading to the recognition of a perfect super- 
vision. In virtue (1) of His omnipresence, and (2) of 
His infinite wisdom, He sees at each instant the whole 
universe as it has been in the infinite past, as it is now, 
and as it will be in the infinite future ; and this being 
as true of any one instant as it is of any other, we 



3 28 OTHER WORLDS THAN OURS. 

recognize the operation of yet a new form of infinity— 
the infinite duration of the Almighty's existence — to 
render yet more inconceivably perfect God's supei 
vision of His universe. 

And now with regard to control. Does the Al 
mighty, who supervises all things, exercise any con- 
trolling action upon the course of events ? 

It need hardly be said that, if God does exercise 
control, apart from the laws which He has assigned to 
His universe, His knowledge of the progress of past 
and future events is not therefore to be called in ques- 
tion, since His own direct action, whether in the past 
or in the future, is quite as much the subject of His 
consciousness (to use this word for want of a better) as 
the action of His creatures or of the laws He has pri- 
marily set them. 

"We know that certain laws have been assigned to 
the universe, and we know also that, so far as our 
very limited experience enables us to determine, these 
laws are never abrogated.* Here I set - altogether 

* All things working thus according to law, however, certain diffi- 
culties suggest themselves which must not be left undealt with, since 
not to consider them might be to leave painful doubts in the minds of 
some who may read these pages. 

In the first place, there is the old question of the relation between 
man's free-will and the absolute foreknowledge of Almighty God. It 
seems clear to many that if all things are foreknown there can be no 
such thing as free-will ; insomuch that some have even felt forced to 
believe that the Almighty, though undoubtedly omniscient, must in a 
sense forego His knowledge of future events so that the actions of men 
may be subject to the control of their will. But in reality we have 
only to consider the analogy of human foreknowledge, to see that there 
is no necessity for any theory so self-contradictory as this. We have 
already considered other attributes of the Almighty as in a siense re- 



SUPERVISION AND CONTROL. 329 

aside, for the moment, the possibility of miracles, and 
consider only the resnlts of experimental or observa- 
tional science. Thus, we are led to the conclusion 
that all things happen according to set physical law? ; 

sembling, though infinitely exceeding in range of action, certain attri- 
butes of man ; let us, then, inquire whether that attribute of man which, 
though imperfect and limited, yet corresponds to the foreknowledge of 
God, affords us any reason for believing that perfect foreknowledge bars 
the exercise of free-will. The answer is obvious at once. We know 
that we often judge, with more or less certainty of conviction, that such 
and such acts will be performed by others, and that yet our anticipation 
in no sense influences the will of the persons who are expected so to 
act. Suppose I remember, for example, that I have left a valuable 
in a room which will presently be passed through by one whom I know 
to be dishonest ; I judge accordingly that the person will purloin the 
valuable. In this case his free-will is not affected by my anticipation ; 
nor would it be though a yet clearer conviction of his. conduct were im- 
pressed upon me. There is, in fact, no conceivable degree of certainty 
on my part which would render him undeserving of punishment for 
stealing the valuable. And so, not to give further instances where the 
matter is so obvious, we see that no conceivable degree of foreknowl- 
edge bars free-will. The infinite and absolute foreknowledge of the 
Almighty is therefore altogether dissociated from the dangerous and 
hurtful belief in a predestination which renders man irresponsible for 
his actions. 

Secondly, the belief in the absolute perfection of the laws according 
to which God rules His universe, insomuch that throughout all the 
worlds in space all things work according to those laws without need 
of special interference on His part, has been thought by many, and is 
painfully felt by some, to oppose itself to our belief in the efficacy of 
prayer. In touching on this point, I wish very carefully to avoid any 
intrusion on matters apart from the general scope of my subject ; but a 
few words may be permitted me on a point which comes close home to 
the hearts of all of us, and which also does seem in a sense associated 
with the matters I have been dealing with. All men, I suppose, pray ; 
though many may in words deride prayer, and though hundreds, without 
expressing doubts, may fail to see any possible utility in the practice, 
because they cannot believe that the action of the physical laws of God 
can be interfered with in answer to the appeal of His creatures. It is 
because I fear lest some of my readers should have felt this difficulty, 



33° 



OTHER WORLDS THAN OURS. 



and without, by any means, adopting the view that the- 
Almighty exercises no special control over His uni- 
verse, we see strong reason to believe that the laws 
which He has assigned to it are sufficient for the con- 

and should find their doubts confirmed by any thing I may here have 
written, that I indicate the explanation which I suppose every one who 
thinks much upon this point would probably be led to. Remembering 
that, on the one hand, it is unreasonable to conceive that God would 
have allowed a belief in the efficacy of prayer to grow, as it has done, 
to be a part of human nature, were that belief founded in a monstrous 
fiction, and tha* on the other hand, it is unreasonable to suppose that 
physical laws are interfered with in response to the millions of prayers 
daily offered by men, the obvious conclusion seems to be that prayers 
are responded to (where it has seemed fitting that they should be) with- 
out interference with natural laws ; that, in fact, the scheme of the Al- 
mighty includes at once the prayers and their response. It seems baf- 
fling, indeed, to human thoughts that such an infinity of varied interests 
should thus be provided for, in a scheme whose extent covers the infini- 
ty of past and future time ; but where infinite wisdom is in question this 
consideration need not trouble us. Nor is this particular mode of con- 
trol inconsistent even with our merely human conceptions of what is 
reasonable. For instance, a father, desirous at once of testing and re- 
warding the obedience of a son, might tell him to go to such a place 
and to open such a box, having beforehand placed therein a reward for 
his son's obedience. Here the fulfilment of the father's request would 
no more result in bringing the gift to the box, than our fulfilment of the 
duty of prayer can cause the laws of Nature to cease or change in their 
operation ; yet obedience would in the one case, as we can conceive it 
does in the other, in reality bring about its own reward. And, further, 
it may be remarked that, precisely as the greater or less certainty of the 
father as to his son's obedience would in no sense affect the latter's 
merit, so neither does the absolute foreknowledge of God as to the 
prayers which His creatures will offer up, affect in any sense the merit 
which He has been pleased to recognize in the sincere performance of 
the act of prayer. 

Lastly, there is the difficulty as to our belief in miracles — that is, in 
events which involve the temporary suspension or alteration of natural 
laws. It must be remembered here that recent physical researches, 
though they have enabled us to interpret so many of the laws of Nature, 
yet tell neither for nor against our recognition of the possibility of 



SUPERVISION AND CONTROL. 33 1 

trol of all things. Indeed, so far as all tilings take 
place in accordance with laws which the Almighty 
must assuredly have Himself ordained, we may say 
that every event which has happened or will happen 
throughout infinite time is the direct work, and indi- 

miracles. It belongs to the very essence of a miracle that it should be 
an event which no physical researches can explain, or indeed can affect 
otherwise than to render it the more inexplicable. The question is, not 
whether such and such an event is more or less wonderful to the un- 
learned Hodge or Styles on the one part, or to a Newton or a Faraday 
on the other, but whether an event can really take place in which the 
laws of Nature have absolutely been annulled and abrogated. I take it, 
for instance, that if we could see a hungry multitude fed with a few 
loaves, and were absolutely certain that so many thousands had been 
satisfied with what would naturally be the food but of a few, our wonder 
would not be greater or less whether we viewed the matter as a laborer 
would, who simply knows what hunger is and what is needed to satisfy 
it, or whether we were familiar with the analysis of bread and com- 
parted the amount of fibrine and albumen contained in the loaves with 
what we knew of the daily or hourly exhaustion of the corresponding 
materials in the human frame. 

The arguments in favor of miracles or against their having occurred 
(of their possibility there need be no question) are the same now as they 
were in less scientific ages. Those who believe in the occurrence of 
miracles argue thus : Man differs from all other terrestrial creatures 
in being responsible to his Creator. Thus between him and Almighty 
God there is a direct relation, which renders it necessary that the will 
of God should be communicated to man. Now, we can conceive no way 
in which such communication can be made in an 'unmistakable manner, 
but by events which involve an unmistakable exercise of a power be- 
longing to God alone — that is, by events of a supernatural character. 
The believer in miracles further argues that nothing tending to prove 
the impossibility (in a natural sense) of an event of this sort can be ac- 
cepted to disprove its occurrence, since what is essentially requisite to 
the very purpose of a miracle is that it should be in a natural sense im- 
possible. Nor is it necessary that any recorded miracle should be in 
itself of a striking or imposing character, so long as its connection with 
the communication of God's will in a special manner is reasonablj 
established, since the triviality or non-triviality of an event whose 
miraculous character is in question is to be judged only by the circum- 



tt 2 



OTHER WORLDS THAN OURS. 



cates the direct purpose and will, of Almighty God. 
Eor need the thought that the Almighty thus seems to 
be made the author of evil as well as of good in any way 
startle us, because we know that what constitutes evil 
or good in our limited vision may by no means be ac- 
cepted as indicative of what is evil or good as the work 
of God. We know, limited as our wisdom is, that evil 
often works to good, so that if the Almighty, whose 
wisdom extends over the never-ending chain of sequent 
events, seems, by permitting evil, to, in a sense, coun- 
tenance it, we are to recognize the sequent good as in 
truth His work, and to regard that which is objectively 
evil (and actually evil in the creature who does it) as 
subjectively good in Him who permits it with a per- 
fect knowledge of all that in the infinity of future time 
is to flow from it. 

Now, it seems conceivable that in reality it is only 
our limited acquaintance with the operation of the 
laws which God has set His universe, which makes us 
regard them as unchanging, and, so to speak, inex- 
orable. There seems, indeed, reason rather to expect 

stances of those for whose instruction the miracle is supposed to have 
been worked. 

The argument against the occurrence of miracles has been already 
considered. As has been pointed out, it not only does not meet the 
argument just stated, but rests on the very fact which constitutes the 
basis of that argument — the fact, namely, that the occurrence of 
miracles is contrary to experience. It is obvious, then, that the con- 
siderations I have urged, as to the nature of God's control over His 
universe, need not be regarded as in the slightest degree affecting the 
belief of men in those direct relations between God and man which 
have been held to involve the necessity of miracles. To speak further, 
however, on this matter would bring me to deal with that subject which 
I have selected to avoid 



SUPERVISION AND CONTROL. 333 

than to deny, that He who made the laws may annul 
or suspend them at His pleasure. 

But I think that this view — though it has been 
entertained bj many thoughtful men, especially be 
cause it seems to give the Almighty a special control- 
ling power over His universe — is in reality inconsistent 
with just conceptions of His infinite wisdom. If His 
wisdom, though inconceivably great, were yet finite, 
we could not suppose that the universe would have 
been so planned (still to use inexact words for want of 
better), and laws of such a nature assigned to it, that 
throughout the infinity of time all things should work 
out the will and purpose of Almighty God. There 
would then, undoubtedly, be continual need of adap- 
tation, change, remodelling — of the annulment of a 
law here, or its suspension there — in order that the 
whole mio'ht not foil to wracK. But where the God 
of ^Nature is infinitely wise, there can be no such neces- 
sity. The whole scheme of the universe must needs 
be so perfect that direct intervention cannot at any 
time be required. 

To sum up, we find ourselves led to the belief that, 
while intervention with the operation of natural laws 
is unnecessary, all the worlds existing throughout space 
are, in a very definite and special manner, watched 
over and controlled by an omnipresent, omnipotent, 
and omniscient Being; that before Him the infinite 
past and the infinite future of the universe are at all 
times sensibly present ; that each the minutest atom 
a lid every the least important event exhibits before 
Him at each instant the perfect history of the limitless 



334 OTHER WORLDS THAN OURS. 

past and future of the universe; and lastly, that Hie 
infinitely perfect consciousness of, and control over, all 
that has been, is, or will be, are infinitely multiplied 
(to use the only available expression) by the infinite 
Juration throughout which His existence extends. 



THE END. 



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LIBRARY OF CONGRESS 




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